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AIR BRAKES 





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AIR BRAKES 



AN UP-TO-DATE TREATISE ON THE WESTINGHOUSE AIR BRAKE 

AS DESIGNED FOR PASSENGER AND FREIGHT SERVICE 

AND FOR ELECTRIC CARS, WITH RULES FOR 

CARE AND OPERATION 



BY 

LLEWELLYN V. LUDY, M. E. 

PROFESSOR OF EXPERIMENTAL ENGINEERINQ, , 
PURDUE UNIVERSITY 
AMERICAN SOCIETY OF MECHANICAL ENGINEERS 



ILLUSTRATED 



AMERICAN TECHNICAL SOCIETY 

CHICAGO 

1918 



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COPYRIGHT, 1917, BY 

AMERICAN TECHNICAL SOCIETY 



COPYRIGHTED IN GREAT BRITAIN 
ALL RIGHTS RESERVED 




©CI.A315SIU 
m W 1919 



INTRODUCTION 



THE HISTORY of braking devices for railroad trains describes 
a long series of mechanisms from the simple hand form to the 
comphcated electric type. Some of these sprang rapidly into 
prominence and then disappeared quite as rapidly into the dump- 
heap. Others persisted for several years, but were finally laid away 
by their friends with evident reluctance. The one device which 
has had an uninterrupted success since the invention by Westing- 
house is the air brake, and today this type of brake is almost exclu- 
sively used on both railroad and electric trains. 

^ The essential quahty of any braking device is rehability. It 
must work in season and out, night and day, in good weather and 
bad, in excessive heat or cold — in fact, nothing under any circum- 
stances must interfere with its efficient action for the lives of many 
passengers and the safety of thousands of dollars worth of property 
absolutely depend upon the abihty of these brakes to bring the train 
to a stop as desired by the engineer. Such a device is the air brake 
and the present equipment is so reliable that railroad accidents are 
almost never due to any fault of the brakes. 

^ The author has chosen the Westinghouse system as being the 
most typical and most widely used and has carefully analyzed the 
various types of equipment for freight and passenger service. 
Copious diagrams indicate the action of the brake under various 
positions of the operating lever and rules for operating and care of 
the equipment make the article especially valuable. The article 
treats as well the types of equipment which have been developed 
especially for electric cars. The treatment of all of the equipment 
is strictly up-to-date and should be of value either to the practical 
railroad man or to the layman who wants the "know how" of things. 




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CONTENTS 

WESTINGHOUSE AIR-BRAKE SYSTEM 

PAGE 

General characteristics of system 10 

Essential elements 10 

Definition of terms 12 

Operation of Westinghouse air brake 13 

Air compressors 14 

Single-stage type 14 

Two-stage type 20 

Disorders of air compressors 24 

Steam compressor governors 25 

Main reservoir 31 

Valves and valve appliances 32 

"0-6" automatic brake valve 32 

"H-6" automatic brake valve 41 

"S-6" independent brake valve 44 

Duplex air gage 47 

"C-6" single-pressure feed 47 

"B-6" double-pressure feed valve 50 

Plain triple valve 53 

Quick-action triple valve 53 

Type "K" freight triple valve 62 

Type "L" triple valve 76 

Pressure retaining valve 87 

Conductor's valve 90 

High-speed reducing valve 91 

"E-6" safety valve 94 

Brakes and foundation brake gear 96 

General requirements 96 

Leverage 99 

Automatic slack-adjuster 101 

Locomotive driver brakes 104 

Locomotive truck brakes 104 

MODERN BRAKE EQUIPMENT 

Fimdamental types 105 

High-speed brake equipment 105 

Double-pressure control or schedule "U" 107 

"LN" passenger-car brake equipment 109 



CONTENTS 

PAGE 

No. 6 "ET" locomotive brake equipment 110 

Functions and advantages 110 

Arrangement of piping, etc Ill 

Names of pipes Ill 

Manipulation of equipment 113 

Distributing valve and double-chamber reservoir 116 

General method of operation 116 

Charging 120 

Service 120 

Service lap 123 

Automatic release 124 

Emergency 124 

Emergency lap 127 

Independent appUcation 127 

Independent release 128 

Double-heading , 131 

Quick-action cyUnder cap 131 

"PC" passenger brake equipment 133 

Characteristics 133 

Special features of 'TC" equipment 133 

Names of various parts and their identification 134 

Charging empty equipment 141 

Release connections 142 

Preliminary service position 143 

Secondary service position 144 

Service position 145 

Service lap position 147 

Over-reduction position 148 

Over-reduction lap position 149 

PreUminary release position 151 

Graduated release position 155 

Release lap position 158 

Release and charging pressure chamber and emergency and service 

reservoirs 158 

Direct release and charging position 159 

Quick-action valve venting 160 

Quick-action valve closed 162 

Westinghouse train air-signal system 165 

Essentials of air-signal system 165 

Reducing valve 167 

Signal valve 167 

Brief instructions for use and care of air-brake equipment 168 



CONTENTS 
AIR BRAKES AS APPLIED TO ELECTRIC CARS 

PAQB 

General survey of systems developed 171 

Hand brakes 171 

Early forms of air brake 172 

Characteristics of modern systems 172 

Details of "SME" brake equipment 174 

Features of "SME" system 174 

Principal working parts 174 

Equipment of non-motor trailers 176 

Proper and improper manipulation 178 

Type "D-EG" motor-driven air compressor 181 

Ty])e "J" electric compressor governor 185 

Tj-pe "AI-18" brake valve . 189 

Duplex air gage 190 

Type "D" emergency valve 190 

Brake cylinder 191 

Conductor's valve 191 

Charging 193 

Service application 193 

Holding brakes appHed 194 

Releasing 196 

Emergency application 196 

Axle-driven compressor equipment 197 

Storage air-brake equipment 197 

Train air signal 199 

Stopping a car 199 



AIR BRAKES 

PART I 



INTRODUCTION 



Braking an Outgrowth of Speed. The development of the many 
accessory appliances with which the rolling stock of our railways is 
fitted has been the subject of a great deal of study and investigation. 
Of the many appliances which have received careful and systematic 
study, the braking apparatus is one of the most important. 

The time when the question of braking first received attention 
dates back farther than the time when highways became sufficiently 
well made and well maintained to permit of vehicles being drawn at 
a moderate rate of speed. When wheeled vehicles, drawn at speeds 
of ten or fifteen miles per hour, first made their appearance, it was 
found necessary to provide means by which they could be easily and 
quickly stopped in case of emergency. The first carts and wagons, 
built for agricultural purposes, were of such construction that the 
resistance of the earth and axle were sufficient to bring them to rest 
in a reasonable length of time on ordinary roads. In cases of steep 
grades, the motion was retarded by one or both wheels being locked 
with chains, or by a stone or piece of timber being chained to the axle 
and dragged along the ground behind the vehicle. 

It is interesting to note that the question of braking has steadily 
increased in importance as the demand for higher speed has increased. 
This applies equally well to all classes of vehicles, including railway 
trains, street and interurban cars, automobiles, and wagons. The 
first forms of braking apparatus adopted have formed the basis of 
almost all brake appliances since employed for the same vehicles. 

Early Forms of Brake. Stagecoach Type. Perhaps one of the 
first forms of brake used was that found on the early stagecoach. 
It consisted of an iron shoe w^hich was chained to the fore part of the 
coach, and it was used only on steep grades. To apply this brake, 
the shoe was removed from its hook under the carriage and placed on 



2 AIR BRAKES 

the ground in front of the rear wheel in such a position that the wheel 
would roll on it. As the wheel rolled on the shoe, the chain became 
taut, with the result that both the shoe and wheel slid over the 
surface of the ground. 

First Railroad Type. A railroad is known to have existed as 
early as 1630, although it would hardly be called by that name today. 
The construction of the track, as well as that of the cars, was almost 
entirely of wood. Even with this crude construction it was found 
necessary to provide a brake to control the speed of the cars on the 
slight grades. The form of brake devised to meet the conditions 
consisted of a wooden lever pinned to the frame of the car at one end 
in such a manner as to permit of its being pressed against the tread 
of the wheel by hand. When not in use, the lever was held off the 
wheel by means of a chain. The principle employed here in resisting 
the motion of the car is the same as that employed today on all 
railroads, namely, of applying the braking or resisting force to the 
periphery of the wheel. 

Developments Due to Steam Locomotive. As railroads increased 
in number and their construction improved, braking apparatus 
became more and more a necessity. As a result, inventors brought 
out a number of simple braking appliances. The question of braking, 
however, did not become a very important or a very serious one 
until the advent of the steam locomotive. Previous to its coming, 
the cars were small and were drawn by animals, and the speeds were 
low; but, with the steam locomotive in existence, an efficient brake 
became an absolute necessity. 

This problem received the close attention of inventors and 
investigators; and, at the close of 1870, the automatic, electro- 
magnetic, steam, vacuum, and air brakes were found in use on the 
railroads in the United States. These types of brakes differed 
chiefly in the manner in which the braking power was obtained. 
Other devices were invented, but could not stand the test of actual 
practice and did not come into prominence. 

Cramer Spring Type. It might be interesting to note briefly 
one or two rather unique types of brakes not included in any class 
yet mentioned. The Cramer brake, brought out in 1853, might be 
mentioned as one of these. Its principal feature consisted of a spiral 
spring, which was connected to the brake staff at the end of each 



AIR BRAKES 3 

car. This spring was wound up by the brakeman before leaving 
the station, and the brake apparatus on each car was under the 
control of the engineer through the medium of a cord. This cord 
was connected to the mechanism of the several brakes and passed 
through the cars, terminating in the cab on the engine. The engineer, 
desiring to stop his train, would shut off the steam and give the 
cord a pull, which action resulted in releasing the coil springs on 
the various cars and applied the brakes by winding up the brake 
chains. 

Loiighridge Chain Tyye. The Loughridge chain brake, another 
unique brake, was introduced in 1855. This brake consisted of a 
combination of rods and chains which extended from a winding 
drum under the engine throughout the entire length of the train. 
This continuous chain joined other chains under each car, which, in 
turn, were connected to the brake levers. The winding drum located 
under the engine was connected by a worm gear to a small friction 
wheel. In operating the brake, a lever in the cab was thrown which 
brought the small friction wheel in contact with the periphery of one 
of the driving wheels, thereby causing the drum to rotate and wind 
up the chain. The movement of the chain, which was experienced 
throughout the entire length of the train, served to actuate levers 
and rods under each car which, in turn, applied the brake shoes to 
the treads of the wheels. 

Hand Types. The early types of hand brakes underwent many 
changes as years went on and as experience suggested improvements. 
Although during many years of early railroading, the braking on all 
trains was done by hand, nevertheless there was a constant desire 
and demand for a practical automatic brake. The rather crude and 
inefficient types already referred to were obtained only after a great 
many failures. Since about 1870, all forms of brakes have differed 
chiefly in but one respect, that is, in the appliances which are used 
in operating the foundation brake gear. The foundation brake gear 
is made up of the rods, levers, pins, and beams located under the 
frame of the car, the operation of which causes the brake shoes to be 
pressed against the periphery or tread of the wheel. The present 
scheme of applying the brake shoe to the periphery of the car wheel — 
which was in use long before the first locomotive made its appear- 
ance — later experience has proved to be the most practicable. 



4 AIR BRAKES 

Many forms of brakes were devised prior to the year 1840, but, 
at that time, few locomotives were equipped with braking apparatus. 
About this period, however, when the locomotive tender began to 
take on some definite form, we find the tender fitted with braking 
appliances. Previously, when brakes were provided, they were 
usually found fitted to the cars only. It is only within the last 
thirty-five years that locomotives have been built with brakes fitted 
to the drivers. Today it is not uncommon to find all wheels on 
both the locomotive and the tender equipped with braking apparatus. 

First Westinghouse Air Type. In 18G9, the first Westinghouse 
air brake made its appearance. This brake is now referred to as 
the ''straight air brake". It was not an automatic brake. It con- 
sisted chiefly of a steam-driven air compressor and storage reservoir 
located on the engine; a pipe line extending 'from this reservoir 
throughout the length of the train, a brake cylinder on each car, and 
a valve located in the cab for controlling the brake mechanism. 
The train line was connected between cars by means of flexible 
rubber hose with suitable couplings. Each car was fitted with a 
simple cast-iron brake cylinder and piston located underneath the 
frame, the piston rod of which connected with the brake rigging in 
such a manner that, when air was admitted into the cylinder, the 
piston was pushed outward and the brake thereby applied. In 
operating the brake, air was admitted into the train line from the 
storage reservoir by means of a three-way cock located in the cab. 
The air was conducted to the brake cylinder under the various cars 
by means of the train pipe. The release of the brakes was accom- 
plished by discharging the air in the various brake cylinders and 
the train pipe into the atmosphere through the three-way cock in 
the cab. This was the simplest and most efficient brake invented 
up to the time of its appearance, and was adopted by many railroad 
companies in this country. 

Westinghouse Plain Automatic. The straight air-brake system, 
however, possessed three very objectionable features: First, in 
case of a break-in-two or of a hose bursting, the brake at once became 
inoperative; second, it was very slow to respond in applying and 
releasing the brakes; and, third, the brakes on cars nearest the 
engine were applied first, causing jamming and surging of the cars^ 
which sometimes proved destructive to the equipment. In order 



AIR BRAKES 5 

to overcome these undesirable qualities, Mr. George Westinghouse 
invented the Westinghouse automatic air brake in lcS72. This form 
of brake, which has since gone out of service on steam railroads, 
was known as the ''plain automatic air brake". This brake retained 
the principal features of the straight air brake, but in addition, 
each car was provided with an air reservoir, which supplied the air 
for operating its particular brake cylinder. The charging of this 
auxiliary reservoir with air, the admitting of this air into the brake 
cylinder, and the discharge of the air from the brake cylinder to the 
atmosphere, were accomplished by an ingenious device known as the 
triple valve. A detailed description of this valve will be given later. 

Vacuum Brake. The vacuum brake was also invented in the 
year 1872, but, on account of its many undesirable features, it never 
gained very great prominence in this country. This brake was 
spoken of as the "plain vacuum brake", and was followed later by 
the "automatic vacuum brake". The principal parts of the air 
brake were, in general, embodied in the vacuum brake. One marked 
difference existed, however, in that, instead of an air compressor, 
an ejector was installed on the locomotive, which exhausted the air 
from the train pipe when the system was in operation. 

At the close of the year 1885, there could be found in use on 
the railroads of the United States a number of different types of 
brakes. These could be grouped into two general classes: con- 
tinuous, or air brakes, and independent, or buffer brakes. In the 
buffer brake, the brake shoes were actuated by rods and levers, 
which in turn received their motion from the movement of the draw- 
bar. It is easily seen that, with such a variety of different forms of 
braking apparatus, it would be impossible to control a train properly 
if it were made up of cars from different railroads having different 
brake systems. 

Work of Master Car Builders* Association. Inierchangeable 
Brake System. The one agency which has had an important part 
in bringing the braking appliances of our railroads to the present 
high standard of perfection is the ^Master Car Builders' Association. 
This association, realizing the increasing demand for the interchange 
of .cars, saw the need of interchangeable brake systems. It was 
principally through the research of their committees that the brake 
systems of today are interchangeable and efficient. 



6 AIR BRAKES 

The first experiment conducted by the committee in 1886 clearly 
showed that any further attempt to use the independent or buffer 
brake was not desirable, on account of the severe shocks resulting 
when stopping the train. The effect of the report of the committee 
was the withdrawal of this type of brake from the attention of the 
railroad officials. This left almost the entire field open to the con- 
tinuous or air-brake system. The committee continued its work 
the following year and, from the results of a large number of tests, 
reported that the best type of brake for long freight trains was one 
operated by air in which the valves were actuated by electricity. 
This type of brake stopped the train in the shortest possible dis- 
tance, reduced all attending shocks to a minimum, was released 
instantaneously, and could be applied gradually. Although the 
results of tests pointed to the superiority of the air brake in which 
the valves were operated by electricity, yet it is only recently that 
a successful system has been adopted. 

From the time of these tests, the different brake companies 
turned their attention to the style of brake represented by the 
Westinghouse "automatic air-brake'* system. In this system, the 
most important parts are the triple valve, located on the brake 
cylinder of each car, and the controlling, or engineer's brake valve, 
located in the cab. By the year 1893, a number of triple valves and 
engineer's brake valves had been placed on the market and repre- 
sentative ones were exhibited at the Columbian Exposition in 
Chicago in that year. 

Triple-Valve Tests. The committee of the Master Car Builders' 
Association, being conscious of the fact that the actions of the valves 
made by the different companies were so widely different, proposed 
a series of tests of triple valves and asked the different companies 
to submit valves for the said tests. The object of the proposed tests 
was to obtain data from which a code of tests for triple valves could 
be formulated which would be satisfactory to all parties concerned. 
The ultimate aim of the committee was to secure triple valves which 
would operate with the same ultimate effect when subjected to 
identical conditions, and which would operate successfully when 
intermingled with each other in a train. 

Such tests were conducted on a specially constructed air-brake 
testing track in the year 1894. Five companies responded with 



AIR BRAKES 7 

valves for the series of tests, of which the valves representing the 
Westinghouse and New York companies gave the best results. 
From the results obtained the committee prepared a code of tests 
for triple valves, which code was soon after adopted by the association 




as standard. As a result of this action, makers of air-brake apparatus 
endeavored to produce triple valves which would give results as 
specified in the code. This naturally led to interchangeable air- 
brake systems— one of the objects which the committee hoped to 
attain. ]\Iany triple-valve tests have since been made, and the 



8 



AIR BRAKES 



code has been changed from time to time to meet new conditions 
which have developed. 

Studying the Air Brake. Air-brake study should be carried on 




from two standpoints, namely, the theoretical and the practical, 
keeping them as closely associated as possible. 

First, the name of every complete part of the air-brake apparatus 



AIR BRAKES 9 

and its connections on the engine, tender, and car should be learned. 
The next thing to be taken up is the function of each part, but 
neglecting the interior mechanism, ports, passages, etc. In other 
words, one should learn how the air brake looks on the outside and 




how it is connected, as shown in Figs. 1, 2, and 3, as this is the basic 
principle of installation of all automatic railway air brakes now in 
service. Until this is so well learned that it can be pictured in the 
mind without reference to the engine, car, or illustration, the 



10 AIR BRAKES 

student is not ready to study the interior construction and opera- 
tion of any part. 

Today there are mainly two air-brake systems in general use 
on steam railroads in this country, namely, the Westinghouse system 
and the New York system. A few years ago the two systems were 
quite different, the construction and operation of the different valves 
being worked out on entirely different principles. Today the 
various parts comprising the two systems are so much alike in both 
appearance and principle of operation that the layman cannot 
distinguish any difference. For this reason it seems advisable to 
confine the work entirely to a discussion of the Westinghouse system. 

WESTINGHOUSE A1R=BRAKE SYSTEM* 

GENERAL CHARACTERISTICS OF SYSTEM 

Brakes are used to prevent the movement of cars or engines 
when at rest and, when in motion, to control the speed while descend- 
ing grades or to stop when it is desired to do so. These results are 
obtained through friction resulting from pressing the brake shoes 
against the wheel faces or treads. An air brake is one in which 
compressed air instead of hand power is used to cause the brake- 
shoe pressure. 

Essential Elements. The automatic air brake has the follow- 
ing ten important parts which, with their connections, are shown 
in Figs. 1, 2, and 3. 

1 . A steam-driven air pump or compressor located on the engine to compress 
the air for use in the brake system and signal system when used. 

2. A main reservoir located somewhere on the engine or tender for the 
following purposes: (a) to receive and store the air compressed by the pump 
or compressor; (b) to act as a cooler for the compressed air and to catch the 
moisture and oil which are precipitated from the air by cooling; (c) to act as 
a storage chamber for excess pressure or backing volume for the purpose of 
releasing the brakes and recharging the air-brake system. 

3. An engineer's brake valve, located in the cab in easy reach of the engineer, 
with feed valve attachment, through which (a) Air from the main reservoir 
may be admitted to the brake pipe either (1) direct, as when charging the train 
or releasing the brakes; and (2) through the feed valve, as when running over 
the road and maintaining pressure in the system, (b) Air from the brake pipe 

*In presenting the discussion and description of the Westinghouse system, free use has 
been made, where necessary, of literature on the subject pubUshed by the Westinghouse 
Company. 



AIR BRAKES 11 

may be allowed to escape to atmosphere when applying the brakes, (c) The 
flow of air to or from the brake pipe and brake systpm may be prevented, as 
when holding the brakes applied. 

4. A (hmhh-poudcd air gage, so connected that one hand indicates the 
main-reservoir pressure and the other indicates the brake-pipe pressure. 

5. An air-pump or compressor governor to control the operation of the 
pump by automatically decreasing or closing off the steam supply to the pump 
to prevent the accumulation of more than the predetermined main-reservoir 
pressure. 

6. A brake pipe, including branch pipe, flexible hose, and couplings, 
which connects the engineer's brake valve and the conductor's valve, with the 
triple valve on each car. Angle and cut-out cocks are provided in the brake 
pipe on each car, the former for opening or closing the brake pipe at any desired 
point in the train, and the latter to cut out, or in, individual triple valves. 

7. A triple valve on each vehicle, to which the brake pipe, the auxiliary 
reservoir, and the brake cylinder are connected by separate openings and which, 
by connecting these openings, control the flow of air between these parts so as 
to enable the auxiliary reservoir to be charged and the brakes to be applied 
and released. The functions of the triple valve may be briefly stated as fol- 
lows: (a) When charging and maintaining the pressure in the brake system 
(1) to permit air to flow from the brake pipe to the auxiliary reservoir; (2) to 
prevent air from flowing from the auxiliary reservoir to the brake cylinder; and 
(3) to keep the brake cylinder open to the atmosphere, (b) When applying 
the brakes (1) to close communication from the brake pipe to the auxiliary 
reservoir; (2) to close communication from the brake cylinder to the atmos- 
phere; and (3) to permit air to flow from the auxiliary reservoir to the brake 
cylinder, (c) When holding the brakes applied, to close all communications 
between the brake pipe, auxiliary reservoir, brake cylinder, and atmosphere. 
(d) When releasing the brakes and recharging the system: (1) to keep the 
brake cylinder open to the atmosphere; (2) to permit the air to flow from the 
brake pipe to the auxiliary reservoir; and (3) to prevent air from flowing from 
the auxiliary reservoir to the brake cylinder. 

8. An auxiliary reservoir, in which the compressed air is stored for apply- 
ing the brake on its individual car. 

9. A brake cylinder provided with a leather-packed piston and piston 
rod connected with the brake levers in such a manner that when the piston 
is moved by the air pressure the brakes are applied. 

10. A pressure-retaining valve, not shown in either Figs. 1, 2, or 3, but 
connected to the exhaust or discharge port of the triple valve. In its ordinary 
or cut-out position it permits the brake-cylinder pressure to be freely discharged 
to the atmosphere, but when cut in, as required when descending heavy grades, 
it retards the discharge of air from the brake cylinder down to a predetermiiKMl 
amount, and then retains that amount when the triple valve is in its release 
position. 

The operation of these parts referred to above will be described 
in detail under the proper heading later in the work. 

The triple valve performs its various functions by variations 
between brake-pipe and auxiliary-reservoir pressures. If the brake- 



12 AIR BRAKES 

pipe pressure is made the higher of the two, then the triple valve 
will move to a position for releasing the brake and charging the 
auxiliary reservoir. But if the auxiliary-reservoir pressure is 
made higher than that in the brake pipe — a condition obtainable 
only through reducing the brake-pipe pressure by the engineer's 
brake valve or conductor's valve, burst hose or pipe, or train parting 
— then the triple valve will move to a position for brake appli- 
cation. 

Definition of Terms. Increase in Brake-Pipe Pressure. When- 
ever air is passing into the brake pipe more rapidly than it is escap- 
ing so as to produce a raise in pressure, it means a brake-pipe pres- 
sure increase, and will cause the triple valves to release the brakes 
and recharge the brake system; but the student must bear in mind 
that there are two sources of drain on the brake pipe which will 
operate to prevent an increase in pressure, namely, leakage from 
the brake pipe through any of its many connections, and also by 
feeding into the auxiliary reservoirs. All of these losses must 
be overcome before a raise in brake-pipe pressure can be obtained. 

The brake-pipe pressure is maintained by a piece of apparatus 
known as a feed valve, which forms a part of the engineer's brake 
valve. This feed valve automatically supplies the brake-pipe 
losses as fast as they take place through any source whatever, 
provided the handle of the engineer's brake valve is kept in running 
position. 

Brake- Pipe Reduction. The term ^'brake-pipe reduction" means 
that air is escaping or being discharged from the brake pipe faster 
than it is being supplied. Therefore, it must be understood that 
losses from the brake pipe which are not supplied will constitute 
a brake-pipe reduction and will cause the triple valves to move 
toward application position. 

Lap. The term "lap" is used to designate the position of the 
engineer's brake valve, triple valve, or distributing valve, in which 
all operative ports are closed to the air in any direction. 

Brake Application. By brake application is meant a sufficient 
reduction of brake-pipe pressure, no matter how made, to cause the 
triple valves to move to application position and, if made through 
the service position of the engineer's brake valve, may consist of one 
or more brake-pipe reductions. 



AIR BRAKES 13 

Service Applicatioii. Service application is accomplished by a 
gradual reduction of brake-pipe pressure, so as to cause the triple 
valves to assume this position and produce the desired result, such 
as is made by operators for a known train stop or slow down. 

Emergency Application. Emergency application is accomplished 
by a quick, heavy reduction of brake-pipe pressure which will cause 
the triple valves to assume the emergency position and produce quick 
action, such as is made by operators with the brake valve, or by 
train men with the conductor's valve, for the purpose of saving life 
or property. It is also made automatically whenever the brake 
pipe is broken or the train parts. 

Operation of Westinghouse Air Brake. When the brakes are 
in operating condition, the pump governor is usually set to maintain 
a pressure of 90 pounds in the main reservoir. The feed valve 
is set to maintain a pressure of 70 pounds in the brake pipe when 
the engineer's brake valve is in running position. The operation 
of the brake is controlled by the engineer's brake valve, which has 
five fixed positions for its handle. These positions named in order, 
beginning from the left, are: release, running, lap, service, and 
emergency. 

To make a service application of the brakes, the handle of 
the engineer's brake valve is placed in service position, thereby 
closing connection between the main reservoir and the brake pipe 
and permitting air to escape from the brake pipe to the atmosphere 
through ports in the valve. The handle of the engineer's brake 
valve is left in this position for a short time only, w^hen it is placed 
in the lap position. 

In the lap position, all working ports are closed and the brakes 
are held applied. 

^Yhen it is desired to release the brake after either a service 
or an emergency application, the handle of the engineer's brake 
valve is placed in release position. In this position, direct connec- 
tion is made between the main reservoir and the brake pipe. The 
handle of the brake valve is left in this position only long enough 
to insure the release of all of the triple valves and then it is placed 
in running position. This is done to prevent an overcharged brake 
pipe. The brakes will release when the engineer's brake valve is 
placed in running position, but they will do so very slowly. 



14 AIR BRAKES 

When it is necessary to make an emergency application, the 
handle of the engineer's brake valve is placed in emergency position 
and direct connection is made between the brake pipe and the 
atmosphere. This causes a sudden reduction of pressure in the 
brake pipe and gives a higher pressure in the brake cylinder than 
is obtained in service applications. If the handle of the engineer's 
valve is left in the emergency position until a brake-pipe pressure 
reduction of from 20 to 25 pounds is obtained and it is then placed 
in lap position, the maximum braking power is obtained. This 
will be made clear when the study of the quick-action triple valve 
is taken up. 

AIR COMPRESSORS 

SingIe=Stage Type. The Westinghouse single-stage air com- 
pressor consists of an air cylinder, in which the air drawn from the 

atmosphere is compressed; a steam cyhnder, 
located above the air cylinder, the two being 
connected by a center piece; and a steam cyl- 
inder valve motioji which for the most part is 
contained in the upper steam cylinder head. 
The compressor is of the double-acting 
direct-connected type, steam being admitted 
alternately to the under and to the upper 
side of the steam piston, causing it to move 
up and down. As the air piston is directly 
coupled to the steam piston by the piston 
rod, it moves up and down with the steam 
piston. On the upward stroke of the air pis- 
ton, the air above it is compressed and dis- 
charged into the main reservoir while the 
space below it is being filled with air drawn 
from the atmosphere. On the down stroke 
Fig. 4. 9Hlchs7eam-Driven this Operation is rcvcrscd. The exhaust steam 
rn. f ^'%^^'^';'''l'' , . is usually piped to the smokestack. 

Courtesy of Westinghouse Air v/ jr x- 

^'^g'peZ^v^n^""' ^^^^^' ^hc comprcssor is built in differ- 

ent sizes. Table I gives the principal dimen- 
sions, actual air delivery, and weight of the single-stage compressors. 
All of the sizes of single-stage air compressors now being built 
operate on the same principle. Fig. 4 illustrates the general appear- 




AIR BRAKES 



15 



TABLE I 

General Dimensions, Capacity, and Weight of Westinghoiise Standard 
Steam=Driveqi Air Compressors 



Diameter of Steam Cylinder 


8 in. 


9| in. 


11 in. 


Diameter of Air Cylinder 


8 in. 


9^ in. 


11 in. 


Stroke 


10 in. 


10 in. 


12 in. 


Steam Admission Pipe 


1 in. 


1 in. 


1 in. 


Steam Exhaust Pipe 


Uin. 


U in. 


1| in. 


Air Admission Pipe 


H in. 


Ih in. 


U in. 


Air Delivery Pipe 


li in. 


11 in. 


U in. 


Nominal Speed, single strokes per 








minute 


12Q 


120 


100 


Actual capacity in cu. ft. of free air 








})er min. actually delivered when 








operating continuously, at above 








speed, against 100 pounds pressure 


20 cu. ft. 


28 cu. ft. 


45 cu. ft. 


Over-all Dimensions: Height 


421 in. 


42i in. 


5U in. 


(Approximate) 








Width 


18 in. 


18i in. 


22 in. 


Depth 


13f in. 


14i in. 


16 in. 


Average Net Weight 


450 lb. 


525 lb. 


850 lb. 



ance of the 9J-inch size. Views of the compressor, with steam and 
air cyUnders and valve mechanism in section, are shown in Figs. 
5 and 6. Figs. 7 and 8 are distorted or "diagrammatic" illustrations 
designed to show as clearly as possible the connections of the various 
ports and passages but not the actual construction of the parts. 

MetJiod of Action in Steam End of Compressor. Considering 
first the steam end of the compressor, and referring to the above- 
mentioned figures, steam from the supply enters at the connection 
marked ''from boiler", Fig. 6 (or "steam inlet", Figs. 7 and 8), 
and flows through the passageways a and a^ (see also Fig. 5), to 
the chamber A, above the main valve 83 and between the pistons 
77 and 79, and through passage e to chamber C, in which is reversing 
valve 72. The supply and exhaust of steam to and from the steam 
cylinder is controlled by the main valve 83, which is a D type of 
slide valve. It is operated by the two pistons, 77 and 79, of unequal 
diameters and connected by the stem 81. The movement of these 
two pistons and the main valve is controlled by the reversing valve 
72, which is in turn operated by the main steam piston 65, by means 
of the reversing rod 71 and the reversing plate 69. As will be 
seen from the following description, the duty of the reversing valve 
72 is to alternately admit or discharge steam from chamber D 



16 



AIR BRAKES 



at the right of piston 77, thus alternately balancing or unbalancing 
this piston. The reversing valve is operated by the reversing rod 
71. This rod is alternately moved up and down by reversing 
plate 69, which engages reversing shoulder j on the upward stroke 

of the steam piston and button k at 
the end of the rod, on the downward 
stroke. 

Chambers A and C are always 
in free communication with each other 
and with the steam inlet through 
port e, e^ as shown in the figures. 
Live steam is therefore always pres- 
ent in these chambers A and C. 
Chamber E, at the left of small piston 
79, is always open to the exhaust 
passage d through the ports t and 
t^, shown in the main valve bushing, 
Fig. 5, and diagrammatically in Figs. 
7 and 8. Exhaust steam, practically 
at atmospheric pressure, is therefore 
always present in chamber E. 

A balancing port .«? runs diag- 
onally to the right in the reversing- 
valve cap nut and meets a groove 
down the outside of the reversing 
valve bush, where it enters the upper 
end of the cylinder through a small 
port in the head. The object of this 
is to assure the same pressure above 
as below the reversing rod, whether 
there is live or exhaust steam in the 
upper end of the cyhnder, thus bal- 
ancing it so far as steam pressure 
is concerned. 

When the reversing slide valve 
72 is in its lower position, as shown in Figs. 5 and 7, chamber 
D is connected (through ports h, h^, re versing- valve exhaust- 
cavity H and ports / and f^) with main exhaust passage d, d\ d^^ 




Fig. 5. Section of Air Compressor 
through Reversing Valve 
Courtesy of Westinghouse Air Brake Com- 
pany, Wilmerding, Pennsylvania 



AIR BRAKES 



17 



and there is, therefore, only atmospheric pressure at the right of 
piston n. 

Therefore, as chamber E, at the left of piston 19, and chamber 
Z), at the right of piston 17 , are both connected to the exhaust, 



MAIM VALVt 
BUSHING 




DI6CMP<$£ 



Fig. 6. Section of Air Compressor through jMain Valve 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

as already explained, the pressure of the steam in chamber A has 
driven the large piston 77 to the right, and it has pulled the smaller 
piston 79 and the main valve 83 with it to the position in Figs. 
6 and 7. The main valve 83 is then admitting steam below piston 



18 



AIR BRAKES 



Iniei-S' 



65 through port h, b\ h\ Piston 65 is thereby forced upward, 
and the steam above piston 65 passes through port c^ c, exhaust 
cavity B of main valve 83, port d, and passage d^, d^ to connec- 
tion Ex, at which point it leaves the compressor and discharges 
through the exhaust pipe into the atmosphere. 

When piston 65 reaches 
the upper end of its stroke, 
reversing plate 69 strikes 
shoulder j on rod 71 , forc- 
ing it and reversing slide 
valve 72 upward sufficiently 
to open port g. Steam from 
chamber C then enters 
chamber D through port g 
and port g^ of the bushing. 
The pressures upon the two 
sides of piston 77 are thus 
equalized or balanced. Con- 
sidering piston 79, the con- 
ditions are different. Cham- 
ber E, as already stated, is 
always open to the exhaust. 
As piston 77 is now bal- 
anced, the steam pressure 
in chamber A forces piston 
79 to the left, drawdng with 
z?/5c^^/ye- pjg^Qj^ ^^ ^j^j main valve 

83 to position shown in 
Fig. 8. 

With main valve 83 in 
the position, steam is ad- 
mitted from chamber A, 
through port c, c^ above 
piston 65 forcing it down; at the same time the steam below this 
piston is exliausted to the atmosphere through port h^, b\ h, 
exhaust cavity B in the main valve, port d, d\ d^ and the exhaust 
pipe connected at Ex. 

When piston 65 reaches the lower end of its stroke, reversing 




Fig. 7. 



Diagram of Westinghouse Compressor 
for the Up-Stroke 



AIR BRAKES 



19 



Inlef-S 



plate 69 engages reversing button A*, and draws rod 71 and reversing 
valve 12 down to the positions shown in Pigs. 6 and 7, and one 
complete cycle (two single strokes) of the steam end of the com- 
pressor has been described. 

Method of Action in Air End of Compressor. The movement 
of steam piston 65 is im- 
parted to air piston 66 by 
means of the piston rod 65. 
As the air piston 66 is raised, 
the air above it is com- 
pressed and air from the 
atmosphere is drawn in be- 
neath it ; the reverse is true 
in the downward stroke. 

On the upward stroke 
of piston 66, the air being 
compressed above it is pre- 
vented from discharging 
back into the atmosphere 
by the upper inlet valve 
86a. As soon as the pres- 
sure in ports r, r^ below 
upper discharge valve 86c 
becomes greater than the 
main reservoir pressure 
above it, the discharge 
valve 86c is lifted from its 
seat. The air then flows 
past this valve down 
through chamber G, out at 
''air discharge" and 
through the discharge pipe 
into the main reservoir. 

The upward movement of the air piston produces a partial 
suction or vacuum in the portion of the cylinder below it. The 
air pressure below piston 66 and on top of the lower left-hand inlet 
valve 86h becomes, therefore, less than that of the atmosphere 
in port n underneath this valve. Atmospheric pressure, there- 




\/Jir 
Discharge 



Fig. 8. 



Diagram of Westinghouse Compressor 
for the Down Stroke 



20 



AIR BRAKES 



fore, raises valve 86b from its seat, and atmospheric air is drawn 
through strainer 106 at "air inlet", into chamber F, and port n 
below the inlet valve 86b, thence, past that valve through ports 
and 0^ into the lower end of the air cylinder, filling same. Air 
cannot enter this part of the cylinder by flowing back from the 
reservoir through D and G and lower discharge valve 86d, since 
this valve is held to its seat by the main-reservoir pressure above it. 

The lower inlet valve 86b seats 
by its own weight as soon as 
the up-stroke of the air piston 
66 is completed. 

On the downward stroke 
of the compressor, the effect 
just described is reversed, the 
air below piston 66 being com- 
pressed and forced out through 
ports p and p^ past lower dis- 
charge valve 86d and through 
chamber G and the air discharge 
pipe into the main reservoir. At 
the same time air is being drawn 
in from the atmosphere through 
"air inlet" through chamber F 
and port Z^ upper inlet valve 
86a and ports m and m'^ into 
the upper end of the air cylinder 
above the air piston 66. 

Two=Stage Type. The 
Westinghouse two-stage air com- 
pressor, known as the "SJ-inch 
cross-compound compressor", is 
controlled or operated by a valve gear quite similar to that used in 
the single-stage type. The following description covers in a general 
way the chief differences in the operation of the two types of com- 
pressors: 

Comparison with Single-Stage Type, The cross-compound 
pump is coming into use as a result of the growing demand for more 
air on long freight trains. Its capacity is about three and one-half 




Fig. 9. 8 J^-Inch Cross-Compound Com- 
pressor, Showing Air-Inlet Side 
Courtesy of Westinghouse Air Brake Company, 
Wilmerding, Pennsylvania 



AIR BRAKES 



21 



times that of the 9^-incli pump shown in Fig. 4. As illustrated in 
Figs. 9 and 10, this pump is of the duplex type, having two steam 




^40^ '• £7 '/e 36 

Fig. 10. Vertical Section of Westinghou.se 8J2-Inch Cross-Compound Compressor 

and two air cylinders arranged with the steam cylinders above 
and the air cylinders below. The high-pressure steam cylinder 
is SJ inches in diameter, and the low-pressure l-ij inches in diameter, 



22 



AIR BRAKES 



both having a 12-inch stroke. The low-pressure air cyhnder is 
14^ inches in diameter, and is located under the high-pressure steam 
cylinder. The high-pressure air cylinder is 9 inches in diameter and 
is located under the low-pressure steam cylinder. The valve gear is 



m D I 




Fig. 11. Diagram of Westinghouse 8 J/^-Inch Cross-Compound Compressor, 

Showing High-Pressure Steam (Low-Pressure Air) Piston 

on the Up-Stroke 

located on the top head of the high-pressure steam cylinder and is 
very similar to that of the 9J-inch pump already described. Figs. 
11 and 12 show diagrammatically a cross section through the pump, 
Fig. 11 showing the parts during an up-stroke of the high-pressure 



AIR BRAKES 



23 



steam side, and Fig. 12 during a down-stroke of the high-pressure 
steam side. The liigh-pressure steam piston is shown on the right 
and the h)w pressure on the left. The high-pressure steam piston, 
with its hollow rod, contains the reversing-valve rod and operates 



m I 




Fig. 12. Diagram of Westinghouse 8i-Inch Cross-Compound Compressor, 

Sliowiug High-Pressure Steam (Low-Pressure Air) Piston 

on the Down Stroke 

the reversing valve in the same manner as that of the 9J-inch pump. 
This valve operates the main valve in the same manner as that 
described in the case of the 9J-inch pump. The main slide valve 
controls the steam admission to, and the exhaust from, both the 



24 AIR BRAKES 

high- and the low-pressure steam cylinders. It is provided with 
an exhaust cavity and, in addition, has four steam ports in its face. 
The two outer and one of the intermediate ports communicate with 
cored passages extending longitudinally in the valve, which serve to 
make the connection between the high- and the low-pressure cylinders 
during the expansion of steam from one to the other. The other 
port controls the admission of steam to the high-pressure cylinder. 

The valve seat has five ports. Of these, the two outside, 
shown in Figs. 11 and 12, lead to the upper and to the lower ends 
of the high-pressure steam cylinder. The second and fourth from 
the right lead to the upper and to the lower ends of the low-pressure 
steam cylinder; and the middle one leads to the exhaust. By 
follo^s'ing the arrows in Figs. 11 and 12, the flow of air and steam 
through the pump can be easily traced. 

The principle of compounding employed in this pump enables 
it to compress air much more economically than is possible with 
the simple or single-stage compressor. 

Disorders of Air Compressors. The compressor is an important 
part of the air-brake system and must be kept in perfect working 
condition. \Yithout its use the brake system is worthless. For 
this reason it is important that it be given proper attention in the 
matter of lubrication, repairs, etc. The Westinghouse Company gives 
the follo\sing directions for remed}4ng disorders of the compressor: 

Compressor Refuses to Start. Cause: Insufl5cient oil, from scant or no 
feed; water in cylinder; worn main-piston rings; or rust having accumulated 
during time compressor has lain idle. Remedy: Shut off steam, take off cap 
nut, put in a tablespoonful of valve oil (not too much), let the oil soak down 
for one or two minutes, and then turn on steam quickly. In many cases when 
the compressor will not start when steam is first turned on, if steam is then 
turned off and allowed to remain off for one or two minutes and then turned 
on quickly, it will start without the use of any oil except that from the lubricator. 

Compressor Groans. Cause: (1) Air cylinder needs oil. Remedy: 

(1) Put some valve oil in air cylinder and saturate piston swab witk valve 
oil, then replace it on the rod. Cause : (2) Steam cyUnder needs oil. Remedy : 

(2) Increase lubricator feed. Leakage past the air-piston packing rings or 
past a discharge valve causes heating, destroys lubrication, and results in groan- 
ing. Piston-rod packing dry and binding is another cause of groaning. 

Uneven Strokes of the Compressor. Cause: Probably (1) leakage past 
air-piston packing rings and sticky air valves: (2) unequal lift of air valves; 

(3) clogged discharge valve passages; or, (4) leaky air valves. Remedy: Locate 
cause, if possible, and correct it by cleaning out clogged or dirty passages, 
adjusting lift of valves, or replacing leaky valves or rings. 



AIR BRAKES 25 

Sloio in Compressing Air. Cause: (1) Leakage past the air-piston 
packing rings, due to poor fit, or wear in cylinder or rings; (2) valves and pas- 
sages dirty; or, (3) air-suction strainer clogged. Kemedy (1) and (2): To 
determine which is causing the trouble, obtain about 90 pounds air pressure, 
reduce the speed to from 40 to 60 single strokes per minute, then listen at the 
"air inlet" and note if air is drawn in during only a portion of each stroke, and 
if any blows back. If the latter, an inlet valve is leaking. If the suction does 
not continue until each stroke is nearly completed, then there is leakage past 
the air-piston packing rings or back from the main reservoir past the air-dis- 
charge valves. The leaking of one of these valves will cause an uneven stroke. 
Remedy: (3) Clean strainer thoroughly. 

Compressor Erratic in Action. Cause: Worn condition of valve motion. 
Remedy: Renew it. 

Compressor Heats. Cause: (1) Air passages are clogged; (2) leakage 
past air-piston packing rings; or, (3) the discharge valves have insufficient lift. 
Remedy: (1) Clean air passages; (2) renew air-piston rings; (3) regulate 
lift of discharge valves to ^ of an inch on the 8|-inch and to -^ of an inch 
on the 10^-inch compressor. A compressor in perfect condition will become 
excessively hot and is liable to be damaged if run very fast and continuously 
for a long time. 

Compressor Pounds. Cause: (1) Air piston is loose; (2) compressor 
either not well secured to boiler or causes some adjacent pipe to vibrate; (3) 
the reversing valve plate 18 is loose; or (4) the reversing rod or plate may 
be worn so that the motion of compressor is not reversed at the proper time. 
Remedy: Repair and renew worn parts and tighten loose connections. 

Steam Compressor Governors. The steam compressor gov- 
ernor, sometimes called the air-pump governor, is used, as the name 
implies, for governing the air pump or compressor, causing it to 
stop operation when it has compressed the air in the main reservoir 
to a certain predetermined pressure and to resume operation when 
the pressure has dropped below this point. 

Single Top "*S" Type. This governor is located in the 
steam supply pipe close to the air compressor. Figs. 13 and 14 
show the governor in closed and open positions. When in operation 
steam enters at B and flov/s past the steam valve 26, when open, 
to the pump at P. The governor is operated by air pressure from 
the main reservoir, which is always open to the connection MR 
and the under side of the diaphragm 46 through a small pipe leading 
from the main reservoir pipe near the engineer's brake valve shown 
in Fig. 1. As long as the main reservoir pressure in chamber a 
below diaphragm 4^ is not able to overcome the pressure of the 
spring 4U acting on the top of the diaphragm, spring 4^ holds the 
diaphragm 4^ down and thereby holds the small pin valve d to 



26 



AIR BRAKES 



its seat. The chamber above the governor piston 28 is open through 
passage b and the small relief port c to the atmosphere, which per- 
mits the spring 31 below piston 28 to hold the latter and the attached 
steam valve 26 in the open position. 

When the main-reservoir pressure in chamber a below dia- 
phragm 46 becomes slightly greater than the spring pressure above 
the diaphragm, the diaphragm is raised, unseating pin valve d 

and allowing air from cham- 



ber a to flow through pas- 
sage b to the chamber above 
piston 28. This forces pis- 
ton 28 down to the closed 
position, compressing piston 
spring 31 and seating steam 
valve 26, thus cutting off 
the supply of steam to the 
air compressor, except for 
the slight amount which can 
pass through the small port 
shown in steam valve 26. 
This is just sufficient to 
keep the compressor oper- 
ating slowly so as to supply 
the air leakage and avoid 
troubles from steam con- 
densation. 

The chamber below pis- 
ton 28 is open to the atmos- 
phere through the drip-pipe 
connection on the left. This 
is to permit the escape of 
any steam that may leak past the stem of valve 26 or air that may 
leak past piston 28. To avoid troubles from freezing and stopping 
up, the drip pipe should be as short as practicable. 

The governor is adjusted by means of adjusting nut 40, which 
regulates the pressure of spring 4i upon the diaphragm. To change 
the adjustment of the governor, remove cap nut 39 and screw down 
regulating nut 40 to increase the main-reservoir pressure or back 




Fig. 13. Westinghouse Type "S" Single-Top 
Steam Compressor Governor Closed 



AIR BRAKES 



27 



off the regulating nut 4^ to lower the main-reservoir pressure, 
replacing the cap nut 39 after the desired adjustment is made. 
The governor is usually set to cut off at 90 pounds main-reservoir 
pressure. 

For many years this t^'pe of governor was the standard and 
was used in all classes of service. It has now been superseded 
by governors of improved design and is used only on comparatively 
short trains and where the 
main-reservoir capacity is 
sufficiently great to supply 
charging demands. 

Double- Top or Duplex 
"SD'' Type. This type of 
governor has been developed 
to operate in connection with 
the engineer's brake valve, 
permitting the air pump to 
anticipate demands upon the 
main reservoir and to have 
an excess pressure stored there 
for releasing brakes and charg- 
ing trains of greater length 
than the usual main-reser- 
voir capacity will permit. 
Its general construction is 
sho'^Ti in Fig. 15. It is 
arranged to obtain what is 
known as "duplex main-res- 
ervoir regulation". As will 
be seen from the cut, the 
"duplex" governor is the 

same as the Type "S" governor except that two regulating portions 
or "tops" are used, with a T or "Siamese" fitting to connect them to 
the steam portion of the governor. The adjustment of the two 
heads varies according to local conditions, but is usually 90 pounds 
for the "low-pressure" and 120 pounds for the "high-pressure" top. 

The low-pressure top, on the left, is connected to a port in 
the brake valve through wliich air from the main-reservoir port 




Fig. 14. Westinghouse T\"pe "S" Single-Top 
Steam Compressor Governor Open 



28 



AIR BRAKES 



flows to the feed valve when the brake-valve handle is in running 
position. When running over the road, therefore, with the brakes 
released, the low-pressure top of the governor controls the operation 




Fig. 15. Westinghouse Type "SD" Duplex Steam Compressor 
Governor Shown in Section 

of the air compressor in the same manner as has been described 
for the Type *'S" governor, and the high-pressure top does not 
operate at all. When an application of the brakes is made, however, 
the relation of the brake-valve ports is changed so as to shut ofl 



AIR BRAKES 29 

the supply of air to the underside of the diaphragm of the low- 
pressure governor top, and its pin valve d remains held to its seat. 
]\Iean\vhile, air from the main-reservoir pipe can flow direct to 
the connection marked MR of the high-pressure governor top and 
to the chamber beneath its diaphragm. This governor top will 
consequently control the operation of the air compressor as 
described for the Type "S" governor until the brakes are released 
and the brake-valve handle again placed in running position. Only 
one vent port, c, should be open, the other being plugged by a small 
screw, 61, as shown in Fig. 15. This arrangement permits the 
compressor to operate while the brakes are released against a com- 
paratively low main-reservoir pressure, which is, however, ample 
to keep the system properly charged and to supply any leakage 
which may exist, and requires it to operate against the maximum 
main-reservoir pressure only during the time that the brakes are 
applied, which relieves the compressor of an unnecessary burden of 
work and at the same time provides for a high main-reservoir 
pressure to insure a prompt release and re-charge of the brakes. 

Doiible-Top "Sf Type, The principal difTerence between 
the ^'SD'' and "SF" types is in the arrangement of the low-pressure 
head, or, as it is called in the "SF" governor, the '^excess-pressure" 
head. The low-pressure head of the *'SD" governor is arranged 
to maintain a fixed main-reservoir pressure during the times that 
the brakes are released, while the excess-pressure head of the ''SF" 
governor maintains a fixed "excess" of main-reservoir pressure 
over the brake-pipe pressure under the same conditions. The 
high- or maximum-pressure heads of both types are alike in con- 
struction and operation. Its general arrangement is illustrated 
in Fig. 16. 

The excess-pressure head of the *'SF" governor has two air 
connections. That marked ABV corresponds to the similar 
connection of the *'SD" governor. That marked FVP leads from 
the feed-valve pipe, so that air, at whatever pressure the feed valve 
is adjusted for, is always present in chamber / above diaphragm 28. 
The total pressure on the top of diaphragm 28 is, therefore, the 
pressure in the feed-valve pipe plus the pressure of spring 27, which 
is usually adjusted for 20 pounds. The main-reservoir pressure 
in chamber d below diaphragm 28 will, therefore, not be able to 



30 



AIR BRAKES 



raise the diaphragm and its pin valve, and thus shut off the com- 
pressor, until it has risen about 20 pounds above the pressure 
determined by the feed-valve setting. Consequently, whether the 



Excess 
Pressure 

Mead 

3P 



■ Moximum 
51 Pressure 




To Pump 



Fig. 16. Westinghouse Type "SF" Duplex Steam Compressor 
Governor Shown in Section 

setting of the feed valve be changed by accident or design, the same 
excess pressure, 20 pounds, is always maintained. The operation 
of the steam and air pistons of the governor are the same as already 
explained for the ''single" and "duplex" types, except that the 



AIR BRAKES 31 

total pressure on top of diaphragm 28 of the excess-pressure head 
is always feed-valve pressure plus 20 pounds instead of a fixed 
pressure, as in the former types. With the feed valve set for 70 
pounds, approximately 90 pounds main-reservoir pressure would 
be obtained and maintained. 

Troubles tvith Steam Compressor. In correcting troubles which 
have been reported in connection with the use of this governor, the 
Westinghouse Company have issued the following instructions: 

If the cutting-out pressure gradually increases without any change having 
been made in the adjustment of the governor, it is probable that dirt has 
accumulated on the pin valve or its seat, thus slightly raising the valve and 
increasing the compression of the regulating spring. 

If the governor fails to stop the compressor when the desired pressure 
has been reached, examine the drip-pipe connection to see that it has not frozen 
or become closed. Also, if the small hole in the spring box becomes closed 
and there is a slight leakage of air past the diaphragm, pressure may accumulate 
above the latter sufficiently to prevent the pin from raising and stopping the 
compressor. 

If, after being stopped by the governor, the compressor fails to start upon 
a slight reduction in air pressure, examine the pin valve for leakage at the 
relief port, c, when the air pressure is a few pounds less than that for which 
the governor is regulated. Also, if the relief port itself should become stopped 
up, the compressor w'ould fail to start when the air pressure fell. 

Keep all parts of the mechanism clean, particularly the strainers, 29, 
Fig. 16, in the air connections. Keep the joints at the stem unions absolutely 
tight to prevent any escape of oil or steam. Oil will escape with even no sign 
of steam leakage, and the compressor is thereby deprived of part of its lubri- 
cation. 

Main Reservoir. The use of the main reservoir is for storing 
an abundant air supply to be used in charging and releasing the 
brakes. A large reservoir is of great importance, especially in 
freight service, since it provides air for an immediate re-charging of 
the auxiliary reservoir without running the pump intermittently 
at high rates of speed. The main reservoir should have a capacity 
of not less than 35,000 cubic inches on passenger engines and not 
less than 50,000 cubic inches on freight. The main reservoir is 
usually located somewhere on the engine, but sometimes it is placed 
on the tender, although the latter location necessitates two extra 
pipe connections between the engine and the tender, which is not 
good practice. A good practice is to (li\ide the main reservoir and 
place half on each side under the running board. 

The air is then delivered to one side and taken out of the other, 



32 



AIR BRAKES 



the two reservoirs being connected. This system has two decided 
advantages over the others, one being that the air is cooled, thus 
causing the moisture to be collected in the reservoir. The other 
advantage is that the distance between the inflow and out-take pre- 
vents much of the dirt and oil from being carried into the brake 
pipe. The main reservoir should always be drained after each trip 
is completed. 

VALVES AND VALVE APPLIANCES 
AUTOMATIC BRAKE VALVES 

Several types of automatic brake valves, or engineer's brake 
valves, have been developed and are now in use on American rail- 
roads. The one most commonly met with is that known as the 
"G-6" type. It is now found in use on most locomotives not equipped 
with what is known as the ''ET" equipment. 

"Q=6" Automatic Brake Valve. The general construction of 
the ''G-6" brake valve is illustrated in Figs. 17, 18, and 19. It 

is of the rotary type, and is 
connected as shown in Figs. 
1, 2, and 3. Air from the 
main reservoir flows to the 
chamber above the rotary 
valve and, by means of a pipe 
leading from the brake-valve 
connections, to the duplex 
air gage (red hand) and com- 
pressor governor. It has pipe 
connections to the main-res- 
ervoir pipe, brake pipe, equal- 
izing-reservoir pipe, gage (red 
hand, main reservoir) and 
governor pipe, and gage 
(black hand, brake pipe) pipe. 
All of these connections are 
clearly shown in Figs. 18 and 19. There are five different positions of 
the brake-valve handle as indicated in Fig. 19. Beginning from the 
left and naming them in order they are as follows : release, running, 
lap, service-application, and emergency-application positions. 




Fig. 17. "G-6" Automatic Brake Valve 

Courtesy of Westinghouse Air Brake Company, 
Wilmerding, Pennsylvania 



AIR BRAKES 



33 



In describing the operation of the brake valve when the handle 
is placed in any of the five different positions, reference will be 
made to the diagrammatic views shown in Figs. 20, 21, 22, 23, and 2-1. 

Running Position. In charging the system, compressed air 
flows from the main reservoir to the brake valve, entering it through 
passage A, Fig. 20, and flowing to chamber A above the rotary 
valve (see cross section of brake valve. Fig. 18). Port j through 




7~3^ 



I "Pipe. 



Fig. 18. Westinghouse "G-6" Brake Valve in Release Position 

the rotary valve registers with port / in the seat, allowing air to 
flow to the feed valve, which is attached directly to the brake valve 
as shown. The feed valve reduces the pressure of the air from 
that carried in the main reservoir to that which is to be carried in 
the brake pipe. From the feed valve the air re-enters the brake 
valve through port i, which has two branches. 

One branch leads to port I in the seat through which the air 
flows to the cavity c in the rotary valve, thence to the equalizing 



34 



AIR BRAKES 



port g in the seat, and through this to the chamber D above the 
equahzing piston in the lower part of the brake valve. 

Chamber D is connected through port s and pipe connections^ 
as shown, to the qualizing reservoir. 

The purpose of the equalizing reservoir is to furnish a volume 
to chamber D above the equalizing piston larger than could be 
permissible within the brake valve proper. 

From the equalizing-reservoir pipe a connection is made to 



Direct /Ipplicafion 
ond Supplu Port- 1 




To6age 
Block Hand ' 
Brake Pipe 
Pressure 

5 and Port- a 
'Equalizing Port 



Feed Port ■ i 



5-p!pplicalion of 
Brake 
Emer^encu Stop 



4 -flpplicalion of Brake 
fServ'ice Stop 

Fig. 19. Westinghouse "G-6" Automatic Brake Valve, Shown in Plan 

the hlack hand of the duplex air gage, which registers the pressure 
in chamber D and the equalizing reservoir. 

The other branch of port i leads from the feed valve to the 
brake-pipe connection at Y and to the underside of the equalizing 
piston. With the brake handle in running position, the feed valve 
maintains a constant pressure — usually 70 pounds is carried in 
freight service — in the brake pipe and on the underside of the equal- 
izing piston as well as the same pressure in chamber D and the 
upper side of the piston. The equalizing-discharge valve m is kept 



AIR BRAKES 



35 



on its seat, due to the fact that, while the pressure on the opposite 
sides of the piston is equal, the area of the upper side is greater by 
an amount equal to the area of the equalizing-discharge valve 
spindle. 

During the time the brake- valve handle is in running position, 
air flows from the main reservoir through the brake valve and the 



To Unclerstde cf Diaphragm 
of Excess Pressure Head 
cf Duplex Furrif 



Engineer's 
Brake Valve 



To Black Hand of 
Duplex /fir Gag^ 




Fig. 20. Horizontal Section of Westinghouse Brake Valve, Showing 
Running Position 

feed valve into the brake i)ipe, keeping the train charged, which 
is the normal condition of the brake system while a train is running 
over the road and the brakes are not being used. 

Application Position. To apply the brakes in service, the 
brake-valve handle is moved to service-application position, which 



36 



AIR BRAKES 



will permit of a brake-pipe reduction. This cuts off all air supply 
to the brake pipe and equalizing reservoir, as shown in Fig. 21, 
and opens the small port e called the preliminary exhaust port, 
leading to chamber J) and the equalizing reservoir. This permits 
air to escape from above the equalizing piston through port e in 



To Underside of Diaphragm 
of Excess Pressure fiead 
of Duplex Fump Governor 



ngmeer s 
Brake Valve 




Fig. 21. Horizontal Section of Westinghouse Brake Valve, Showing Service Position 

the rotary valve seat, cavity y in the rotary valve, and the direct 
appHcation and exhaust port h to the atmosphere. This reduces 
the pressure of the air on top of the equalizing piston below the 
pressure of the air in the brake pipe under the piston. This con- 
dition causes the piston to lift, carrying the equalizing-discharge 
valve from its seat and allowing air from the brake pipe to escape 



AIR BRAKES 



37 



throiio^li the opening vi past the valve and thence through passage n 
and service exhaust fitting into the atmosphere. 

Without the equahzing reservoir the pressure in chamber J) 
would drop almost instantly to zero, and consequently it would be 
nearly impossible to make a moderate brake-pipe reduction. With an 



To Underside cf'Diaphragm 
of Efcess Pressure Head 
cf Doplei' Pump Gather nor 



f^nt^tneers 
Brake Valine 



To/ftmosphere 



ToBlackfiandof 
Duplex /fir Gage 




Equalizing 
Reservoir 



Brake Pipe 



1 



Fig. 22. Horizontal Section of Westinghousc Brake Valve, Showing Lap Position 

equalizing reservoir of sufficient capacity, it takes (3 to 7 seconds 
to make a reduction of 20 pounds, which is slow enough to permit 
of the reduction to be stopped at any desired point as indicated by 
the air gage by moving the brake-valve handle to /ap position. 
When the equalizing-discharge valve lifts, the discharge of 
air from the brake pipe is rapid, decreasing in amount slowly as 



38 



AIR BRAKES 



the pressure in the brake pipe approaches the pressure in chamber 
D, and the equahzing piston causes the equaUzing-discharge valve 
to close, stopping further discharge of air from the brake pipe. 
This gradual stopping of the brake-pipe discharge prevents the 
air from surging in the brake pipe, a condition which tends to cause 



vzr. 



To Underside cf Diaphragm 
of Excess Pressure Mead 
cf Duplex Pump Go^erncr 




^—Brake Pipe 



Fig. 23. Horizontal Section of Westinghouse Brake Valve, 
Showing Release Position 

an undesired movement of the triple-valve pistons, which might 
cause some of the head brakes to release. 

The length of time that the air will continue to discharge from 
the brake pipe after the brake-valve handle has been placed in 
Zap position depends upon whether the train is a long or short one. 
With a short train, the brake-pipe volume is small and will not 



AIR BRAKES 39 

take as long to discharge as in the ease of a long train where the 
brake-pipe volume is great. It can be readily seen that the equal- 
izing reservoir, together with the equalizing piston, is nothing 
more than an automatic means of measuring the amount of air to 
be discharged from the brake pipe and to govern the rate of flow 
to the atmosphere. 

Lap Position. Lap position of the brake valve, as illustrated 
in Fig. 22, prevents the movement of air to or frrm any ])art of 
the brake equipment through the brake valve. 

This position of the brake-valve handle on locomotives equipped 
with either type of governor previously described causes the low- 
pressure, or the under, side of the diaphragm in the excess-pressure 
head to become inoperative, due to the feed valve being cut off 
from the main reservoir. What air under pressure is left in the 
feed valve escapes through the vent port in the governor. This 
permits the compressor to pump up a supply of air under high 
pressure in the main reservoir to insure a quick release and recharge 
of the brake pipe. 

Lap position is the holding position — the position used when 
it is desired to hold the brake applied for any considerable length 
of time. 

Release Position. The brakes in the train are released by 
placing the brake-valve handle in release position. This opens 
direct communication through the brake valve between the main 
reservoir and the brake pipe, increasing the pressure in the brake 
pipe and releasing the brakes throughout the train. 

When the brake valve is in release position, as shown in Fig. 
23, air from the main reservoir flows through port a in the rotary 
valve to cavity b in its seat, then tlirough cavity c in the rotary 
valve to port /, and thence directly into the brake pipe. At the 
same time, air in cavity c also flows through the equalizing port 
g, to chamber D above the equalizing piston and to the equalizing 
reservoir. Air also flows from the main reservoir through port j 
in the rotary valve into the preliminary-exhaust port e and to 
chamber J). 

While in the release position, air from the main reservoir flows 
through the warning port r in the rotary valve to the direct appli- 
cation and exhaust port k and the atmosphere with considerable 



40 



AIR BRAKES 



noise. This loud exhaust indicates to the engineer that the handle 
of the brake is in release position and attracts his attention in case 
the handle is left in that position by mistake. 

After the handle has been in release position the proper length 
of time, it is moved to the running position, which closes the warning 
port, stops the direct flow of air from the main reservoir to the 



7b Underside of Diaphragm 
of Excess Pressure Head 
of Di/plex Pump GOi'ernor 



Engineerb 
Brake Val^e 



ToBlackHondof 
Duplex /fir Go^e 




Brake Pipe 



i 



Fig. 24. 



Horizontal Section of Westinghouse Brake Valve, 
Showing Emergency Position 



brake pipe, chamber Z), and the equalizing reservoir, and opens the 
supply of air to these parts through the feed valve. In this position, 
the brake pipe, chamber D, and the equalizing reservoir are charged 
up and maintained at the standard pressure by the feed valve. 

The brakes can be released and the brake pipe and system 
re-charged by placing the brake-valve handle in running position 



AIR BRAKES 



41 



directly without first being j)lace(i in release position, hut a much 
longer time will he required. 

Emergency-Applicatioti Position. When it is desired to make 
the shortest possible stop, the brake-valve handle is i)laced in emer- 
gency position, as illustrated in Fig. 24. In this position the brake 
pipe is opened directly to the atmosphere through the large port /, 
cavity c, and port A*, causing a sudden and rapid drop in brake-pipe 
pressure. In this position, cavity p in the rotary valve connects 




Fig. 25. "H-6" Automatic Brake Valve 
Courtesy of Westinghouse Air Brake Company, 
Wilmerding, Pennsylvania 

the feed port / and the preliminary exhaust port e to the exhaust 
port k, thus allowing the air in the feed port, chamber 1), and the 
equalizing reservoir to escape to the atmosphere. The whole 
emergencij-applicatio7i action depends solely upon the suddenness 
of the brake-pipe reduction. 

"H=6" Automatic Brake Valve. The '11-6" automatic brake 
valve not only performs the functions of the ''G-G" brake valve 
but has some additional features necessary for its use in connection 
with the *'No. C" distributing valve and the "S-G" independent 



42 



AIR BRAKES 



Feed Valve 
i'PipeJap ^g 



brake valve of the *'ET" locomotive-brake equipment. In this 
brake valve, the feed valve is not directly attached to the body of 
the valve but is located elsewhere in a convenient place and con- 
nected by suitable pipes. Its general appearance is shown in Fig. 

25, while Fig. 26 shows 
two views, the upper one 
being a horizontal sec- 
tion through the top 
case, showing the rotary 
valve seat, also showing 
the different positions of 
the handle, the lower one 
being a vertical section. 
In describing the 
operation of the brake 
valve, the different posi- 
tions will be taken up in 
the order in which they 
are most generally used. 
As shown in Fig. 26, 
there are six positions for 
the brake-valve handle. 
Beginning from the ex- 
treme left, they are: 
releasCy running, holding, 
lap, service, and emer- 
gency. In the operation 
of the valve the air flows 
through ports in a man- 
ner quite similar to that 
of the '^G-6" brake valve. 
For this reason, the flow 
of air through the "H-6" brake valve, with the handle in its different 
positions, will not be traced. 

Release and Charging Position. The purpose of this position 
is to provide a large and direct passage from the main reservoir 
to the brake pipe, to permit a rapid flow of air into the latter (1) 
to charge the train brake system; (2) to quickly release and re-charge 




Fig. 26. 



^ni Pipe Tap ^4^ 

E^quoUzing Reservoir 

Plan and Sectional Elevation of Westinghouse 
"H-6" Automatic Brake Valve 



AIR BRAKES 43 

the brake; but (3) not to release tlie locomotive brakes if they 
are applied. If the handle is allowed to remain in this position, 
the brake system would be charged to main-reservoir pressure. 
To avoid this, the handle must be moved to running or holding 
position. To prevent the engineer from forgetting this, a small port 
discharges feed-valve-pipe air to the atmosphere in release position. 

Running Position. This is the proper position of the brake- 
valve handle (1) when the brakes are charged and ready for use; 
(2) when the brakes are not being operated; and (3) to release 
the locomotive brakes. This position affords a large direct passage 
from the feed-valve pipe to the brake pipe, so that the latter will 
charge up to the pressure for which the feed valve is adjusted. 

If the brake valve is in running position when uncharged cars 
are cut in, or if, after a heavy brake application and release, the 
handle of the automatic brake valve is returned to running position 
too soon, the governor will stop the compressors until the difference 
between the hands on duplex gage Xo. 1, Fig. 92, is less than 20 
pounds. The stopping of the compressor from this cause calls 
the engineer's attention to the seriously wrong operation on his 
part, as running position results in delay in charging and is liable 
to cause some brakes to stick. Release position should be used 
until all brakes are released and nearly charged. 

Service Position. This position gives a gradual reduction 
of brake-pipe pressure to cause a service application. The gradual 
reduction of brake-pipe pressure is to prevent quick action, and 
the gradual stopping of this discharge is to prevent the pressure 
at the head end of the brake pipe being built up by the air flow- 
ing from the rear, which might cause some of the head brakes to 
^'kick-off". 

Lap Position. This position is used while holding the brakes 
applied after a service application until it is desired either to make 
a further brake-pipe reduction or to release the brakes. All ports 
are closed and the excess-pressure head of the governor is made 
inoperative, permitting the pump to increase the main-reservoir 
pressure to the pressure at which the high-pressure head will cause 
it to stop. 

Release Position. This position is used for releasing the train 
brakes after an application without releasing the locomoti^^e brakes. 



44 



AIR BRAKES 



When the brake-pipe pressure has been increased sufficiently to 
cause this, the handle of the brake valve should be moved to either 
running or holding position; the former when it is desired to release 
the locomotive brakes, and the latter when they are to be still held 
applied . 

Holding Position. This position is so named because the 
locomotive brakes are held applied while the train brakes are being 
released and their auxiliary reservoirs recharged to feed-valve pres- 
sure. The only difference between the running and holding posi- 
tions is that in the former the locomotive brakes are released, while 
in the latter they are held applied. 

Emergency Position. This position is used (1) when the most 
prompt and heavy application of the brakes is required, and (2) 
to prevent loss of main reservoir air and insure that the brakes 
remain applied in event of a burst hose, a break-in-two, or the 
opening of a conductor's valve. Plug 29, Fig. 26, is placed in the 
top of the case at a point to fix the level of an oil bath in which the 
rotary valve operates. Valve oil should be used. 

"S=6" Independent Brake Valve. The general appearance 
of this valve is shown in Fig. 27. Fig. 28 shows two views of the 

''S-6" brake valve; the lower one 
being a vertical section through 
the center of the valve, and the 
upper one a horizontal section 
through the valve body, show- 
ing the rotary valve seat and the 
different positions of the valve 
handle. There are five positions 
,of the brake-valve handle which, 
beginning from the extreme left, 
are : release, running, lap, sloiv ap- 
plication, and quick application. 
This brake valve is used in connection with the "H-6'' auto- 
matic brake valve and is to permit the engineer to operate the 
locomotive or independent brakes through the distributing valve 
independently of the train brakes. 

Running Position. This is the position that the independent 
brake valve should occupy at all times when the independent brake 




Fig. 27. 



Westinghouse "S-6" Independent 
Brake Valve 



AIR BRAKES 45 

is not in use. It can be noted that if the automatic brake valve 
is in running position and the independent brakes are being operated, 
they can be released by simply returning the independent valve to 



f£3 nl'Fipe Tap j-rV § "ripe Tap 




Fig. 28. Plan and Sectional Elevation of Westinghouso "S-fi" 
Independent Brake \'alve 

running position, as the application-cylinder pressure can then 
escape through the release pipe and the automatic brake vahe. 

Slow- Application Position. This position is used for light 
or gradual applications of the independent or locomotive brake. 



46 



AIR BRAKES 



Quick- Application Position. This position is used for quick 
applications of the independent or locomotive brake. 

Lap Position. This position is used to hold the independent 
or locomotive brake after the desired cyHnder pressure is obtained. 
In this position all communication between ports is closed. 

Release Position. This position is used to release the pressure 
from the application cylinder when the automatic brake valve 
is not in running position. 

The supply pressure in the independent brake valve is limited 
by a reducing valve to 45 pounds. Connected to the handle of 




Fig. 29. Diagrams Showing Positions of Valve Handles for Westinghouse 
Automatic and Independent Brake \'alves 

the independent brake valve is a return spring, the purpose of which 
is to return the handle from the release to the running position, 
or from the quick-application to the sloiv-application position. The 
automatic return from release to running is to prevent leaving the 
handle in that position and make it impossible to operate the inde- 
pendent brake by the automatic brake valve. The spring return 
from quick application to sloiv application is to give a resistance to 
unintentional moving of the valve handle to quick-application 
position when only a slow application is desired. 

The operation of the ^'H-6" and ^^S-6" brake valves will be 
studied further in connection with the study of the ''ET" equipment. 



AIR BRAKES 



47 




Fig. 30. Westinghouse 
Duplex Air Gage 



The plan view of both the 'TI-G" and ''S-G" brake valves shown 
in Fig. 29 presents a little more clearly the different positions of 
the brake-valve handles. 

Duplex Air Gage. The duplex air gage previously referred 
to is located on a convenient place in the cab in plain view of the 
engineer. In the ordinary equipment only 
one gage is required. In the ''ET" equip- 
ment two are provided. The gage, see Fig. 
30, is of the Bourdon type and has two pipe 
connections to the brake valve, one of which 
is in constant communication with the main 
reservoir (red hand) and the other is in con- 
stant communication with the equalizing 
reservoir (black hand). The second gage 
furnished with the "ET" equipment has 
one of its two pipes connected to the brake cylinder (red hand) and 
the other to the brake pipe (black hand). 

FEED VALVES 

The function of the feed valve has already been explained. 
In the "G-6" brake valve it forms a part of the valve. The two 
forms most commonly found in 
service are the single-pressure and 
double-pressure types. 

"C = 6" Single = Pressure Feed 
Valve. This feed valve is of the slide- 
valve type and consists of two 
portions, the supply and regulating 
portions. Its appearance detached 
from the brake is shown in Fig. 31. 
Figs. 32 and 33 show actual sections 
taken through the spring box and 
through the slide valve. Figs. 34 
and 35 are diagrammatic sections 
illustrating the operation of the valve and will be referred to in the 
description of its action when in service. 

The supply portion consists of a slide valve 7 and a piston 6. 
The slide valve 7 opens or closes communication from the main 
reservoir to the brake pipe, and is moved by the piston 6, which is 




Fig. 31. 



Westinghouse "C-6" 
Feed Valve 



48 



AIR BRAKES 



operated by main-reservoir air entering through passage a on one 
side or by the pressure of the piston spring 9 on its opposite side. 
The regulating portion consists of a brass diaphragm 17, on 
one side of which there is the diaphragm spindle 18, held against 
the diaphragm by the regulating spring 19, and on the other side 
a regulating valve 12, held against the diaphragm or its seat, as 
the case may be, by spring 13, Chamber L, on the face of the 
diaphragm, is open to the brake pipe through passage e and d. 




''ig. 32. Section of Westinghouse ♦'C-6" 
Feed Valve through Spring Box 



Fig. 33. Section of Westinghouse "C-6" 
Feed Valve through Slide Valve 



The feed valve is adjusted by screwing regulating nut W in or out, 
thus increasing or decreasing the pressure exerted by the spring 
on the diaphragm. 

This feed valve, when applied to the ''G-6" brake valve, is 
usually adjusted for 70 pounds brake-pipe pressure. Suppose 
spring 19 to be compressed so as to exert a force equivalent to a 
70-pound air pressure on the opposite side of the diaphragm. Then, 
as long as the air pressure in the brake pipe and chamber L is less 
than 70 pounds, the spring holds the diaphragm over as far to the 



AIR BRAKES 



49 



left as possible, as shown in Fig. 35. This holds the regulating 
valve ^;^ off its seat, thus opening port K, which permits air to 
flow through port K and from passage // to chamber G at the back 
of the supply piston 6. Consequently, as long as the air pressure 
in G, h, e, and d is less than 70 pounds, the higher main-reservoir 
pressure on the opposite side of piston 6 forces it to the extreme 
left, compressing spring 9 and opening port c, as shown in Fig. 35. 
Air, therefore, continues to flow from the main reservoir through 
a, c, and d to the brake pipe, increasing its pressure and the pressure 
in chamber L, acting on diaphragm 17 y until it reaches 70 pounds. 




Suj 



'ppji/p Delivery 



sAit 



p Q d^OQ^ 



WWUUU 




^A^^tWVVVV 



Fig. 34. Diagrammatic Section of Westing- 
house "C-G" Feed \'alve in Closed Position 



Fig. 35. Diagrammatic Section of Westing- 
house "C-6" Feed Valve in Open Position 



The air pressure on the diaphragm is then able to overcome the 
spring pressure on the opposite side and force the diaphragm to 
the right by ^'buckling" it slightly in that direction. This allows 
the regulating-valve spring 13 to return the regulating vahe 12 
to its seat, which closes port K. Chambers G and // are then no 
longer open to the brake-pipe passage d at 70 pounds pressure 
and, being small, are instantly raised to main-reservoir pressure 
by the slight leakage of air past the supply piston, which is made 
loose-fitting for this purpose. As the air pressures become nearly 
equal on the opposite sides of the supply piston, the piston spring 



50 



AIR BRAKES 




Fig. 36. Westinghouse "C-6" 
Reducing Valve 



9 forces the piston and its slide valve to closed position, Fig. 34, 
which prevents further flow of air from the main reservoir to the 
brake pipe. The operation of the valve as described, after the 

pressure in the brake pipe has reached 
70 pounds is almost instantaneous, so 
that the brake-pipe pressure is held con- 
stant at 70 pounds until it is slightly 
reduced by leakage, so that its pressure 
on diaphragm ^7 is no longer able to 
withstand the pressure of the regulating 
spring, which then forces the diaphragm 
back, lifting the regulating valve from 
its seat and again opening port K. 

The feed valve acts as a maintain- 
ing valve in this manner, keeping the 
brake-pipe pressure constant at the 
amount for which the regulating valve is adjusted as long as the brake- 
valve handle is in proper position for the feed valve to be operative. 

When the *'C-6" type feed valve is 
fitted for pipe connections to be used in 
connection with the distributing valve 
of the "ET" equipment, it is called a 
reducing valve. It h usually adjusted 
to reduce to 45 pounds pressure. The 
arrangement used is illustrated in Fig. 36. 
"B=6" Double=Pressure Feed Valve. 
The "B-6" feed valve is furnished with 
the high-speed and double-pressure con- 
trol apparatus, and also with the *'ET" 
equipment, to permit the use of either 
low- or high-brake pipe pressure. The 
features of this feed valve are the 
same as for the ''C-6" feed valve with the exception of having 
a regulating handle in place of a regulating nut. The extreme 
movement of the regulating handle is controlled by stops, as shown 
in Fig. 37. To adjust this valve, slacken the screw which allows 
the stops to turn around the spring box. The regulating handle 
should then be turned until the valve closes at the lower brake-pipe 




Fig. 37. Westinghouse "B-6" Feed 

Valve, Showing Valve and Pipe 

Bracket Complete 



AIR BRAKES 



51 



pressure desired, the stop should then be brought in contact with 
the handle pin, at which point it should be securely fastened by 
the tightening screw. The regulating handle should then be turned 
until the higher brake-pipe pressure is obtained and the stop is 
brought in contact with the handle pin and securely fastened. 
The usual and recommended pressures for low and high pressures 
are 70 pounds and 110 pounds, respectively. 

The ''B-G" feed valve, like the "C-C feed valve, is also used 




Fig. 38. "B-6" Feed Valve, Showing Valve Removed 

from Pipe Bracket 

Courtesy of Westinghouse Air Brake Company, 

Wilmerding, Pennsylvania 

as a reducing valve. When used in this capacity it is fitted to a 
pipe bracket as illustrated in Fig. 38. 



TRIPLE VALVES 

In the study of the triple valve it is well to keep in mind that 
its essential parts consist of a cylinder fitted with a piston, the 
movement of which operates a slide valve. As long as the pressure 
remains the same on each side of the piston it cannot move, but 
when the pressure on one side is changed the piston will move 
toward the side having the least pressure. It is of vital importance 
that this principle be thoroughly understood, as practically all 
automatic devices of the air brake are constructed along this line. 
This principle, as stated by the Westinghouse Company, is as 
follows: 



52 



AIR BRAKES 



The devices used in connection with the air brake, which are automatic 
in their action, and of which the triple valve is one, depend for their operation 
upon the movements of one or more diaphragms or pistons. The piston or 
diaphragm is a movable partition separating two sources of pressure. As long 
as these pressures are equal no movement occurs, but as soon as the equality 
of pressure is destroyed, and the pressure on one side becomes higher than that 
on the other, the piston or dia- 
phragm tends to move toward the 
lower pressure and, as soon as the 
balance of pressure is again restored, 
the tendency to move ceases. This 
condition holds true whether the 
pressures involved are due to com- 
pressed air or to springs, or to a 
combination of the two. 




Fig. 39. Plain Triple Valve for 
Air Brake Equipment 

Courtesy of Westingkouse Air 
Brake Company, Wilmer- 
ding, Pennsylvania 




Fig. 40. 



Section through Westinghouse Plain 
Triple Valve 



In the case of the triple valve, the variations in pressure neces- 
sary to cause it to operate are due to the increase or decrease in 
brake-pipe pressure caused by movements of the engineer's brake 
valve, burst hose, opening of conductor's valve, etc., on one side 
of the triple-valve piston, or on the other side of the piston by a 
decrease in the auxiliary-reservoir pressure caused by a flow of air 
into the brake cylinder from the auxiliary reservoir. 

As previously stated, the triple valve forms one of the most 
important parts of the air-brake equipment. The different West- 



AIR BRAKES 



53 




inghoiise air-brake equipments make use of the following types 
of triple valves: plain, quick-action, "K", and ''L". The first 
two types mentioned are rapidly 
passing out of service and those 
of later development are taking 
their place. 

Plain Triple Valve. The 
plain triple valve, the general 
appearance of which is shown in 
Fig. 39 and in vertical section 
in Fig. 40, has a east-iron body 
with pipe connections to the 
brake pipe BP, to the auxiliary 
reservoir R, and to the brake cyl- 
inder C, and has an outlet to the 
atmosphere shown by dotted and 
full lines to the right of port p. 

The operating parts consist of a slide valve 6, in which the 
graduating valve 7 moves, the piston 5, and the graduating stem 
8, with its spring 9. The 
graduating valve is at- 
tached to the stem of 
piston 5 by a pin shown 
in dotted lines. 

Quick=Action Triple 
Valve. The quick-action 
triple valve, Fig. 41, is 
shown in vertical section 
in Fig. 42. Its construc- 
tional features are quite 
similar to those of the 
plain triple valve, one of 
the noticeable differences 
being that the operating 
piston and slide valve 
occupy a horizontal posi- 
tion, while in the plain triple valve they have a vertical position. 
It also differs from the plain triple valve in having additional quick- 



Fig. 41. Westinghouse Quick-Action 
Triple Valve 







Fig. 42. 



Westinghouse Quick-Action Triple Valve 
Shown in Section 



54 



AIR BRAKES 



action parts, consisting of an emergency piston 8, emergency valve 
lOy and check valve lo. This triple valve is arranged so as to be 
bolted to the pressure head of the brake cylinder in passenger 
equipments or to the cast-iron auxiliary reservoir in freight equip- 
ments, thus making the brake-pipe connection the only pipe con- 
nection necessary to the triple valve. 




unuxHiory 
IReservoir 



Plain Triple Vohe 






-BP 



^ 



-Cut Out Cock 



^ Brake 
ik Cylinder 



•zzzzzzzzzzzzzzi 




WVWVWVWWVVblVI 
Piston 



Broke Pipe 



Fig. 43. Diagram of Westinghouse Plain Triple Valve, Showing 
Running and Release Position 

The plain triple valve was developed to overcome the defects 
of the straight air brake, chief among which may be mentioned 
the following: a brake that was inoperative in event of a train 
parting; a brake that could not be used successfully in trains of 
over ten cars in length; and a brake requiring considerable time 
to operate. 

The plain triple valve overcame these defects in a large measure 
but soon had to give way to a more refined type of triple valve, 
a valve whose action was more rapid and did not give such severe 
shocks between cars in long trains — say 50 cars — when an emergency 
application of the brakes was made. 



AIR BRAKES 



55 



The qiilck-actiou triple valve overcame the defects of the 
plain triple valve. The general operation of these two valves is 
so much alike that a description for either type will api)ly to the 
other with the exception of the quick-action or emergency feature. 

It will be remembered that the brake pipe extends from the 
engineer's brake valve on the locomotive throughout the train, 
the connections between the locomotive and cars being made by 
a hose and coupling. The essential pipe equipment on each car 




Broke Pipe 



Fig. 44. Diagruin of Westinghouse Quick-Action Triple Valve, Showing 
Running and Release Position 

is the brake pipe, and a branch pipe which connects the triple valve 
to the brake pipe through a cut-out cock. In giving the description 
of the action of both the plain and the quick-action triple valves, 
reference will be made to diagrammatic views shown in Figs. 43 
to 48. Like the engineer's brake valve, the triple valve is spoken 
of as having certain definite positions, such as running or release, 
service, service-lap, and emergency positions. 

Running Position. Air enters the triple valve through port 
e, Figs. 43 and 44, to chamber / and through passages g to chamber 



56 AIR BRAKES 

h, in which the triple valve piston 5 moves. The air pressure in 
chamber h, acting on the face of the piston, forces it to its extreme 
position to the right, which is release and charging position. In 
this position air can flow from chamber h around the piston through 
feed groove i in the bushing and k in the piston seat into chamber 
m, and thence through the pipe connection at R, as shown, to the 
auxiliary reservoir. 

From the figures it will be seen that the triple-valve piston 
5 has a stem on which are two collars. Between these two collars 
is a slide valve 6, shorter than the distance between the collars 
on the piston stem, so that there is a certain amount of clearance 
or **lost motion" between the piston stem and the slide valve. 

The function of this slide valve 6 is to make proper connections 
between the space m (auxiliary-reservoir pressure) and the brake- 
cylinder port r in the seat of the valve; or between the brake- 
cylinder port r and the exhaust port p, also in the seat; or to close 
these ports — according to the positions to which the slide valve is 
moved by the triple-valve piston in order to perform certain func- 
tions. In the release position shown, air at auxiliary pressure is 
acting above and on all sides of the slide valve, but cannot flow 
past or through it since all ports through the valve are closed. The 
exhaust cavity n in the face of the valve, however, makes an opening 
across from the brake cylinder port r in the seat to the exhaust 
port p, so that the brake cylinder is then connected through the 
pipe connection to the triple valve and the ports named to the exhaust 
opening and atmosphere. Any compressed air contained in the 
brake cylinder will flow to the atmosphere, thus permitting the 
release spring acting on the opposite side of the piston to force 
it back to the release position and release the brake shoes from the 
wheels. 

The normal condition of the triple valve when the train is 
running over the road and the brakes are not being used is with 
the triple-valve pistons and slide valve in release position, the brakes 
released, and the auxiliary reservoirs charged and maintained at 
the pressure for which the feed valve — engineer's brake valve — is 
adjusted. 

Service Position, As the brake pipe is connected to the chamber 
h, Fig. 45, of each triple valve, a reduction in brake-pipe pressure 



AIR BRAKES 



57 



will lower the pressure on the brake-pipe side of tlie trij)le-valve 
piston below that of the auxiliary reservoir on the oj)p()site side. 
The higher auxiliary-reservoir pressure will then cause the piston 
to move in the direction of the weaker pressure, thereby closing 
communication between chamber h and the auxiliary reservoir 
through feed groove i. Attached to the piston stem is a pin valve 
7 called the ''graduating valve", which when seated, Fig. 4(), closes 
communication between port w leading from chamber m to the 




rOi 



Brake Pipe 



3 



Fig. 45. Westinghouse Plain Triple Valve, Showing Service Position 



graduating-valve seat in the slide valve and the service port z leading 
from the graduating-valve seat to the face of the slide valve. The 
first movement of the triple-valve piston unseats the graduating 
valve 7, so that the air in chamber ??z, entering port u\ flows to the 
service port z. 

There is a small amount of clearance between the slide valve 
6 and the collar, or "spider", on the end of the triple-valve piston 
stem, so that the first movement of the piston, which closes the 
feed groove i and opens the graduating valve 7, does not move the 
slide valve but brings the spider on the stem against the end of 



58 



AIR BRAKES 



the valve. Further movement of the piston causes the shde valve 
to move until it has closed communication between the brake- 
cylinder port r and the exhaust port p and opened port r to the 
auxiliary reservoir through port z and w, as shown in Fig. 45. The 
piston then comes into contact with the graduating stem and the 
resistance of the graduating spring, combined with the reduction 
in the auxiliary-reservoir pressure then taking place, prevents 
further movement of the parts. The valve is then in service position 




Brake Fipe 



Fig. 46. Westinghouse Plain Triple Valve, Showing Service Lap Position 

and air from the auxiliary reservoir flows through the service port 
to the brake cylinder, forcing its piston outward and applying 
the brake. While the brake-cylinder pressure rises, that in the 
auxiliary reservoir falls and tends to become lower than that in 
the brake pipe. As soon, however, as the pressure on the auxiliary- 
reservoir side of the triple-valve piston falls slightly below that on 
the brake-pipe side, the higher pressure causes the piston to move 
back — toward release position — until the graduating valve is seated, 
closing communication between ports w and z. This further flow 
of air from the auxiliary reservoir — the pressure in which is then 



AIR BRAKES 59 

practically equal to that in the brake pipe — prevents further move- 
ment of the triple-valve piston toward release position, because 
the slightly higher pressure on the brake-pipe side of the piston, 
which was able to move the piston and graduating valve alone, 
is not sufficient to move the slide valve. The triple valve is then 
in service-lap position. 

If a further reduction in brake-pipe pressure is made, the 
reduction in pressure on the brake-pipe side of the triple-valve 
piston below that on the auxiliary-reservoir side causes the piston 
and its attached graduating valve to move to the same position 
as for the first service application of the brakes. The slide valve, 
however, is already in service position, consequently as soon as the 
graduating valve is opened air from the auxiliary reservoir flows 
to the brake cylinder and increases the pressure therein, thus in- 
creasing the pressure of the brake shoes against the wheels. If 
the brake-pipe reduction is continued indefinitely, the auxiliary- 
reservoir pressure will continue to fall and the brake-cylinder pres- 
sure to rise until they become equal, or "equalize". This occurs 
at about 50 pounds cylinder pressure when carrying 70 pounds 
brake-pipe pressure w^ith a properly proportioned cylinder and 
auxiliary reservoir. Nothing is gained in reducing the brake-pipe 
pressure below the equalization point in service applications. 

Service-Lap Position. When the triple valve is in service lap, 
Fig. 46, and assuming that there is no leakage, the brake-pipe and 
auxiliary-reservoir pressures will remain balanced and the brake- 
cylinder pressure held constant until the brake-pipe pressure 
is further reduced, in order to apply the brakes harder; or increased 
in order to release the brakes. 

The brake-cylinder leakage, as well as brake-pipe leakage, is 
generally very severe and it is not good policy to keep brakes applied 
for too great a period at one time, permitting the pressure in the 
brake system to leak off. 

Release and Recharge. To release the brakes and recharge 
the auxiliary reservoir, air is admitted to the brake pipe. This 
increases the pressure on the brake-pipe side of each triple-valve 
piston above that on the other side, causing the piston and slide 
valve to move back to release position, which permits the air in 
the brake cylinder to flow to the atmosphere through the triple- 



60 



AIR BRAKES 



valve exhaust port, thus releasing the brakes. The charging of 
the auxiliary reservoir has been explained under "Running Position" 

Emergency Position, Up to this point, all statements made 
regarding the operation of the triple valve have applied equally 
to the plain, or quick-action triple valve, but during an emergency 
application their action is different. 

When the piston and slide valve of the plain triple valve move 
to the emergency position, Fig. 47, the brake-cylinder port r is un- 




c 



Brake Pipe 



3 



Fig. 47. Westinghouse Plain Triple Valve, Showing Emergency Position 



covered and air from the auxiliary reservoir flows past the end of 
the valve directly through port r into the brake cylinder until the 
brake-cylinder and auxiliary-reservoir pressures become equalized. 
The pressure obtained in the brake cylinder is no higher then when 
a full-service application is made, but the maximum pressure is 
obtained more quickly. 

When the piston and slide valve of the quick-action triple 
valve move to the emergency position, Fig. 48, port s in the slide 
valve registers with port r in the seat, allowing air to flow from the 



AIR BRAKES 



61 



auxiliary reservoir to the brake cylinder. Port s is small, however, 
and in this position the slide valve also opens port t in its seat, 
allowing air to flow from chamber m through port t to the chamber 
above the emergency piston 8. The other side of emergency piston 
8 is connected to the brake cylinder, in which there is no air pressure, 
consequently the emergency piston is forced downward, pushing 
the emergency valve 10 from its seat and allowing air in chamber Y 
above the check valve 15 to flow past the emergency valve 10 to 
chamber X and the brake-cylinder. Brake-pipe air in a below the 




Fig. 48. Westinghouse Quick- Action Triple Valve, Showing Emergency Position 

check valve 15, then raises the check valve and flows to the 
brake cy Under through the passages mentioned. During an emer- 
gency application, therefore, the quick-action triple valve supplies 
air to the brake cylinder from the brake pipe as well as from the 
auxiliary reservoir. 

Approximately 60-pound brake-cylinder pressure is obtained 
on emergency applications, the air from the brake pipe increasing 
the cylinder pressure about 20 per cent above the maximum obtain- 
able with a full-service application. 



62 AIR BRAKES 

This "venting" the brake-pipe pressure into the brake-cyHnder 
aids the speed of an emergency apphcation, as each triple valve 
reduces the brake-pipe pressure sufficiently to set the next triple 
valve in the train to emergency. 

The release after an emergency application is obtained in the 
same manner as for a service-application release. 

The plain triple valve is now only used for locomotives in 
freight and switching service that are not equipped with the "ET" 
distributing valve. 

Type "K" Freight Triple Valve. The standard form of quick- 
action triple valve commonly used in freight service has until 
recently proved very satisfactory. In the last few years, however, 
with heavier locomotives capable of handling 100-car trains fitted 
with air-brake equipment, they have failed to meet all the require- 
ments. Realizing the changed conditions and the importance of 
meeting them, the Westinghouse Company has developed and 
perfected the "K" triple valve. 

Objections to Other Valves Overcome by " K" Type. Some of 
the undesirable features of the standard quick-action triple valve, 
which the "K" triple overcomes are as follows: 

(a) The failure of a portion of the brakes in a long train to apply. 

(b) A complete release of the brakes at the forward end of the train 
before the brake-pipe pressure which has brought this about can reach the triple 
valves near the end of the train. This action permits the slack to run out hard, 
and creates excessive strains on the draft gears, often resulting in a break- 
in-two. 

(c) Overcharging the auxiliary reservoirs at the forward end of the train 
while releasing the brakes. The result of this action is a reapplication of the 
forward brakes when the brake-valve handle is placed in running position. 

The outward appearance of the 'Tv" triple valve when attached 
to the auxihary reservoir is so much like the standard quick-action 
triple that a thin web is cast on the top part of the body as a dis- 
tinguishing mark. The designating mark "K-l" or 'Tv-2" is also 
cast on the side of the body. The "K" triple is made in two sizes 
— the "K-l" for use with the 8-inch freight-car brake cylinder, 
and the ''K-2" with the 10-inch freight-car brake cylinder. Fig. 49. 

This ''K" triple valve embodies every feature possessed by the 
standard quick-action triple valve and three additional ones, 
namely, quick service, uniform release, and uniform re-charge. It 



AIR BRAKES 



G3 



operates in perfect harmony with the standard triple and often 
improves the action of the latter when the valves are mixed in the 
same train. The two types of valves have many parts in common 
and are interchangeable. The standard triple may be transformed 
into the *'K" triple by preserving all of the old parts except the 
body, slide-valve, bush, and graduating valve. This transformation 
can be done at a minimum cost when the valves are returned to the 
works for heavy repairs. 

The above-mentioned features of quick action, quick service, 
uniform release, and uniform re-charge have proved so desirable 
that the valve has been 
accepted as standard by 
so manv railroads that it 
can be said to be the 
''standard" freight triple 
valve of today. 

Q II ick-Service Fea- 
ture. The quick-service 
feature brings about a 
more uniform and a 
quicker application of 
the brakes in a long train 
during service applica- 
tions. 

The rate of brake- 
pipe reduction for service 
applications in the brake 

system is determined by the exhaust port in the brake valve 
and by the frictional resistance of the pipe. These being con- 
stant, it is plain that the longer the train the slower will be the 
pressure reduction in the brake pipe, and, as the distance from the 
head of the train increases toward the rear of long trains, only a 
very slow reduction, if any, takes place, and consequently a very 
slow application, if any at all, takes place. This slow rate of brake- 
pipe reduction not only results in a slow application but many 
times in the failure of individual brakes to apply. This is due to 
one of two things, namely, the air from the auxiliary reservoir pass- 
ing back to the brake pipe through the feed groove ; or, in case of a 




Fig. 49. Westinghouse Type "K" Freight Triple Valve 



64 AIR BRAKES 

movement of the triple- valve piston, by the air leaking out past the 
packing leather in the brake cylinder. 

The quick-service feature gives a rapid serial operation of 
all brakes in service appHcation. This is accomplished by using 
the principle of the standard quick-action triple valve in emergency 
applications, namely, that of discharging brake-pipe air into the 
brake cylinder; that is, in service applications some air from the 
brake pipe passes into the brake cylinder. The result is that the 
quick-service feature insures the operation of every brake, reduces 
the amount of air exhausted at the engineer's brake valve and the 
possible loss of air due to flowing back through the feed groove, 
and effects a saving of air. 

Uniform Release.' Uniform release tends to permit the rear 
brakes to release as soon as those at the head of the train. The rate 
of increase of brake-pipe pressure takes place more and more slowly as 
the distance from the head of the train increases; consequently, 
in long trains the head end brakes are fully released before the rear 
brakes have commenced to release. The uniform-release feature 
is accomplished by automatically restricting the exhaust of air 
from the brake cylinder in the forward portion of the train and 
allowing the others to release freely. This retarded release of the 
forward brakes is due to the increased pressure which exists in the 
forward end of the brake pipe when the brake valve is in release 
position. The effect is noticeable on about the first thirty cars 
of a long train. 

Uniform Re-Charge. Uniform re-charge permits the auxiliary res- 
ervoirs through the entire length of the train to re-charge uniformly. 
With the ordinary quick-action triple valve, the slowness in brake- 
pipe pressure increase in long trains permitted the head end aux- 
iliary reservoirs to become overcharged while those at the rear end 
were undercharged; consequently, when the brake-valve handle 
was returned to running position the head-end brakes would re-apply. 
The uniform re-charge of the auxiliary reservoirs is due to the fact 
that when the valve is in the retarded-release position, the ports 
connecting the brake pipe with the auxiliary reservoir are auto- 
matically restricted. In other words, as long as the exhaust from 
the brake cylinder is retarded, the recharge is restricted. This 
feature not only prevents the overcharging of the auxiliary reservoirs 



AIR BRAKES 



65 



on the front end of the train but, by drawing less air from the brake 
pipe, permits the increase in brake-pipe pressure to travel more 
rapidly to the rear cars where it is most needed for releasing and 
re-charging those brakes. 

Fig. 50 is a vertical cross section and end view of the ''K" 
triple valve and the names of the various parts are as follows: 2 
valve body; 3 slide valve; ^ main piston; 5 piston ring; 6 slide-valve 
spring; 7 graduating valve; 8 emergency piston; 9 emergency-valve 
seat; 10 emergency valve; 11 emergency- valve rubber seat; 12 check- 
valve spring; IS check-valve case; 11^. check-valve case gasket; 



2'^ Z3 za 




i Pipe Plug 



Fig. 50. Westinghouse Type "K" Triple Valve, Shown in End View and Actual Section 

15 check-valve; 16 air strainer; 17 union nut; 18 union swivel; 
19 cylinder cap; 20 graduating stem nut; 21 graduating stem; 
22 graduating spring; 2S cylinder-cap gasket; 21^. bolt and nut; 
25 cap screw; 27 union gasket; 28 emergency-valve nut; 29 retarding 
device body; SI retarding stem; SS retarding spring; S5 graduating 
valve spring. 

The different recognized positions of the parts of a type *'K" 
triple valve are six in number, namely, full-release and charging, 
quick-service, full-service, lap, retarded-release and charging, and 
emergency positions. In explanation of the operation of the valve. 



66 



AIR BRAKES 



reference will be made to the diagrammatic views of this device 
shown in Figs. 51 to 56 and, for the sake of clearness, the descrip- 
tion given in literature published by the Westinghouse Company 
will be largely made use of. 

Full-Release and Charging Position. In this position air from 
the brake-pipe flows through passage e, Fig. 51, cylinder-cap ports 
/ and g to chamber h on the face of the triple-valve piston; thence 



Auxiliary Reservoir ^ v. 

R r~_ J 



Brake Cylinder 
C 




i pipe tap 
Brake Pipe 



Fig. 51. Type "K" Triple Valve, Shown in Full- Release and Charging Position 

Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

through feed groove i, now open, to chamber R above the slide 
valve, which is always in free communication with the auxiliary 
reservoir. In the "K" triple valve, the feed groove i is of the same 
dimension as that of the old standard triple valve. Air flows from 
"the brake pipe to the auxiliary reservoir, as described, until their 
pressures become equalized. 

Quick-Service Position. To make a quick-service application 
of the brakes, the air pressure in the brake pipe, and thereby in 



AIR BRAKES 



67 



chamber h, Fig. 52, is gradualJ\' reduced. As soon as the pressure 
in chamber h has been sufficiently reduced below that in chamber 
R on the other side of the triple-valve piston, the higher pressure 
on the auxiliary-reservoir side of the piston is able to overcome 
the friction of the piston 4 ^^^ its attached graduating valve 7 
and to move these parts to the right imtil the shoulder on the end of 
the piston stem strikes against the left-hand end of the slide valve. 



Auxiliary RcsERVOiff 

R 



Brake Cylinder 

c 




I PIPE TAP 

Brake Pipe 

BP 



Fig. 52. Type "K" Triple Valve, Shown in Quick-Service Position 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

The latter is then moved to the right until the piston strikes the 
graduating stem 21, which is held in place by the compression of 
the graduating spring 22. The parts of the valve are then in the 
position shown in Fig. 52. The first movement of the piston 4 
closes the feed groove i and prevents air from feeding back into the 
brake pipe from the auxiliary reservoir, and at the same time the 
graduating valve opens the upper end of port z in the slide valve. 
The movement of the latter closes the connection between port r 



68 AIR BRAKES 

and the exhaust port p and brings port z into partial registration 
with port r in the shde-valve seat. Air from the auxihary reservoir 
then flows through port z in the shde valve and port r in the seat 
to the brake cylinder. 

At the same time, the first movement of the graduating valve 
connects the two ports o and q in the slide valve through the cavity 
V in the graduating valve, and the movement of the shde valve 
brings port o to register with port y in the slide-valve seat and port 
q with port t. Consequently, the air in chamber Y flows through 
ports y, 0, V, q, and t, thence around the emergency piston 8, which 
fits loosely in its cylinder, to chamber X and the brake cylinder. 
When the pressure in chamber Y has reduced below the brake-pipe 
pressure remaining in a, the check valve 15 is raised and allows 
brake-pipe air to flow past the check valve and through the ports 
above mentioned to the brake cylinders. The size of these ports 
is so proportioned that the flow of air from the brake pipe to the 
top of emergency piston 8 is not sufficient to force the latter downward 
and thus cause an emergency application, but at the same time 
takes enough air from the brake pipe to cause a definite local reduc- 
tion in brake-pipe pressure at that point, which is transmitted in 
like manner to the next triple valve, and in turn to the next, thus 
increasing the rapidity with which the brake-pipe reduction travels 
through the train. 

Full-Service Position. With short trains, the brake-pipe 
volume being comparatively small will reduce more rapidly for a 
certain reduction at the brake valve than with long trains. Under 
such circumstances it might be expected that the added reduction 
at each triple valve by the quick-service feature would bring about 
so rapid a brake-pipe reduction as to cause quick action and an 
emergency application when only a light application was intended, 
but this is automatically prevented by the triple valve itself. From 
Fig. 52 it will be noted that in the quick-service position port 2; 
in the slide valve and port r in the seat do not fully register. Never- 
theless, when the train is of considerable length, the opening is 
sufficient to allow the air to flow from the auxiliary reservoir to 
the brake cylinder with sufficient rapidity to reduce the pressure 
in the auxiliary reservoir as fast as the pressure is reducing in the 
brake pipe; but if the brake-pipe reduction is more rapid than that 



AIR BRAKES 



69 



of the auxiliary reservoir, which may be the case on short trains, 
the difference in pressure on the two sides of piston 4 becomes 
sufficient to shghtly compress the graduating spring and moves 
the sUde valve to the position shown in Fig. 53 called full service. 
In this position, quick-service port y is closed, so that no air flows 
from the brake pipe to the brake cylinder; also, in full-service posi- 
tion ports z and r are fully open, allowing the auxiliary-reservoir 



Auxiliary Resepvoip 

R 



Brake Cylinder 

c 




rpIPE TAP 

Brake Pipe 

BP 



Fig. 53. TjTDe "K" Valvo Shown in Full-Service Position 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

pressure to reduce more rapidly, so as to keep pace with the more 
rapid brake-pipe reduction. 

Zap Position. When the brake-pipe reduction ceases, air 
continues to flow from the auxiliary reservoir through ports z and 
r to the brake cylinder until the pressure in the chamber R becomes 
enough less than that of the brake pipe to cause piston 4 and grad- 
uating valve 7 to move to the left until the shoulder on the piston 
stem strikes the right-hand end of slide valve 3. As the friction 



70 



AIR BRAKES 



of the piston and graduating valve is much less than that of the slide 
valve, the difference in pressure which will move the piston and 
graduating valve will not be sufficient to move all three; conse- 
quently, the piston stops in the position shown in Fig. 54. This 
movement has caused the graduating valve to close port z, thus 
cutting off any further flow of air from the auxiliary reservoir to 
the brake cylinder and also to port o, thus preventing further flow 



Auxiliary Reservoir 



Brake Cylinder 

c 




I" PIPE TAP 

BRAKE PIPE 
BP 



Fig. 54. Type "K" Triple Valve Shown in Lap Position 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

of air from the brake pipe through the quick-service ports. Con- 
sequently, no further change in air pressures can occur, and this 
position is called lajp because all ports are lapped or closed. 

It will be seen that the exact position of the slide valve 3 in 
lap position depends upon whether its previous position was that 
of quick service, Fig. 52, or full service, Fig. 53. If the former, 
the lap position assumed would be quick-service lap position, as 
shown in Fig. 54. If the slide valve had previously moved to full- 



AIR BRAKES 71 

service position, however, the lap position assumed would be fulU 
service lap position, in which the shde valve would still remain in 
full-service position. Fig. 53, but with the graduating valve moved 
back so as to blank ports z and o in the slide valve, and with the 
shoulder on the piston stem in contact with the right-hand end of 
slide valve 3, as shown in Fig. 54. About 20 pounds brake-pipe 
reduction will give full equalization. 

Retarded-Release and Charging Position. The "K" triple valve 
has two release positions, namely, full release and retarded release. 
It is well known that in a freight train, when the engineer releases 
the brakes, those cars toward the front, receiving the air first, will 
have their brake-pipe pressure raised more rapidly than those in 
the rear. With the old standard apparatus, this is due to two 
things: (1) the friction in the brake pipe; (2) the fact that the 
auxiliary reservoirs in the front begin to re-charge, thus tending 
to reduce the pressure head by absorbing a quantity of air and 
holding back the flow from front to rear of the train. The retarded- 
release feature overcomes the second point mentioned, taking advan- 
tage of the first while doing so. The friction of the brake pipe 
causes the pressure to build up more rapidly in the chamber h of 
the triple valves tow^ard the front end of the train than in those 
at the rear. As soon as the pressure is enough greater than 
the auxihary-reservoir pressure remaining in chamber R — after 
the application as above described — to overcome the friction of 
piston, graduating valve, and slide valve, all three are moved toward 
the right until the piston stem strikes the retarding stem 31. The 
latter is held in position by retarding spring 33. If the rate of 
increase of the brake-pipe pressure is small — as, for example, when 
the car is near the rear of the train — it will be impossible to raise 
the pressure in chamber h three pounds higher than that in the 
auxiliary reservoir on account of the flow of air which is going on 
at the same time from chamber h through feed groove i into the 
auxiliary reservoir, the triple-valve parts will remain in this position, 
as shown in Fig. 51, the brakes will release and the auxiliary reser- 
voirs re-charge, as described under ''Full Release and Charging". 
If, however, the triple valve is near the head of the train and the 
brake-pipe pressure builds up more rapidly than the auxiliary 
reservoir can re-charge, the necessary excess of pressure in chamber 



72 



AIR BRAKES 



li over that in the auxiliary reservoir will be attained quickly and 
will cause the piston to compress retarding spring 33 and move the 
triple valve parts to the position shown in Fig. 55. 

Exhaust cavity n in the slide valve now connects port r leading 
to the brake cyhnder with port y to the atmosphere, and the brake 
will release; but, as the small *'tail-port" extension of cavity n 
is over exhaust port p, the discharge of air from the brake cylinder 



Auxiliary Reservoir 

R 



^RAKE Cylinder 

c 




i pipe tap 
Brake Pipe 



Fig. 55. Type "K" Triple Valve Shown in Retarded-Release and Charging Position 

Courtesy of W estinghouse Air Brake Company, Wilmerding, Pennsylvania 

to the atmosphere is quite slow. In this way, the brakes on the 
front end of the train require a longer time to release than those 
on the rear. This feature is called the retarded release, and, although 
the triple valves near the locomotive commence to release before 
those in the rear, as is the case with the standard quick-action 
triple valve, yet the exhaust of air from the brake cylinder in 
retarded-release position is sufficiently slow to hold back the release 
of the brakes at the front end of the train long enough to insure 



AIR BRAKES 



73 



a practically simultaneous release of the brakes on the train as a 
whole. This permits of releasing the brakes on very long trains at 
low speeds without danger of a severe shock or break-in-two. 

At the same time, the back of the piston is in contact with the 
end of the slide-valve bush, and, as these two surfaces are ground 
to an accurate fit, the piston makes a tight ''seal" on the end of 
the bush except at one point, where a feed groove is cut in the 



Auxiliary Rcservoii? 

R 



Brake Cylinder 

c 




Fig. 5G. Type "K" Triple Valve Shown in Emergency Position 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 



piston to allow air to pass around the end of the slide-valve bush 
into chamber R and the auxiliary reservoir. Fig. 55. This feed 
groove is much smaller than the standard feed groove i in the piston 
bush, so that when the triple-valve piston is in retarded-release 
position, the re-charge of the auxiliary reservoir takes place much 
more slowly than when it is in full-release position. This feed 
groove is larger in the 'lv-2" than in the "K-l" triple valve so as to 



74 



AIR BRAKES 



maintain the proper rate of recharge of their respective auxiliary 
reservoirs in retarded-release position. 

As the auxiliary reservoir j^ressure rises and the pressures on 
the two sides of piston 4 become nearly equal, the retarding spring 
31 forces the retarding stem, piston, slide valve, and graduating 




Fig. 57. Westinghouse Type "KC" Combined Freight Brake Equipment 
(Upper) and Type "KD" Detached Freight Brake Equipment (Lower) 

valve back to the full-release position shown in Fig. 51, when the 
remainder of the release and re-charging will take place as described 
above under "Full Release and Charging". 

Emergency Position, Emergency position is the same with 
the "K" triple valve as with the standard quick-action type. Quick 
action is caused by a sudden and considerable reduction in brake- 



AIR BRAKES 76 

pipe pressure below tliat in tlie auxiliary reservoir, no matter hew 
caused. This fall in break-pipe pressure causes the difi'erence 
in pressure on the two sides of piston 4 to increase very rapidly, 
so that by the time the piston has traveled to its full-service position, 
as already explained, there is sufficiently hi^ijher pressure on the 
auxiliary-reservoir side of the triple-valve piston to cause it to 
compress the graduating spring 22, forcing back the stem and 
spring until the piston seats firmly against the gasket 2S, as shown 
in Fig. 56. The resulting movement of the slide valve opens port i 
in the slide-valve seat and allows air from the auxiliary reservoir 
to flow to the top of emergency piston 8, forcing the latter down- 
ward and opening emergency valve 10. The pressure in chamber 
F, being thereby instantly relieved, allows the brake-pipe pressure 
to raise the check valve lo and flow rapidly through the chambers 
Y and X to the brake cylinder until brake-cylinder and break- 
pipe pressures nearly equalize, when the check valve is forced to 
its seat by the check-valve spring, preventing the pressure in the 
cylinders from escaping back into the brake pipe again. The 
^emergency valve, being held open by the emergency piston, will 
consequently return to its seat when the auxiliary-reservoir and 
brake-cylinder pressures have nearly equalized. At the same time, 
port s in the slide valve registers with port r in the slide-valve seat 
and allows air from the auxiliary reservoir to flow to the brake 
cylinder. But the size of ports s and r is such that comparatively 
little air gets through them before the brake pipe has stopped venting 
air into the brake cylinder. This sudden discharge of brake-pipe 
air into the brake cylinder has the same effect on the next triple 
valve as would be caused by a similar discharge of brake-pipe air 
to the atmosphere. In this way each triple valve applies the next. 

The release after an emergency is effected in exactly the same 
manner as after a service application, but requires longer time, 
owing to the high brake-cylinder and auxiliary pressures and lower 
brake-pipe pressures. 

Fig. 57 illustrates two different types of freight-brake equip- 
ment in which the type 'Tv" triple valve is used. The lower figure 
represents the equipment usually found installed on steel hopper- 
bottom coal and coke cars, while the upper figure shows that usually 
found on wood box and gondola cars. 



76 



AIR BRAKES 



Type "L" Triple Valve. Tlie type "L" triple valve is the 
oiiteome of a demand for a brake capable of handling heavy fast 
passenger trains with a, greater degree of safety, flexibility, and 
comfort of passengers than the standard qniek-action triple valve 
could give. It is used in connection with what is known as the 
L. N. Passenger Car equipment. 

In order that trains may be controlled easily and smoothly 
when running at either high or low speeds, and that stops may 




FiR. 5S. Type "L" Triple Valve, Showing Safety Valve in Place 

Courtestj of H't'stinghouse Air Brake Com pa in/, 

Wilmercling, Pennsylvania 

be made quickly and with the least liability of wheel sliding, the 
brake apparatus must provide the following essential features of 
operation : 

(a) A small brake-pipe reduction must give a moderate brake-cylinder 
pressure and a moderate but uniform r(Mardation on tlu^ train as a whole. 

(b) It must be possible to make a heavy-service reduction quickly but 
without liability of quick action. 



AIR BRAKES 



77 



(c) It must be possible to graduate the release as well as the application 
of the brakes. 

(d) To insure the ability to obtain brake applications in rapid succession 
and to full power, a quick recharging of the auxiliary reservoirs is necessary. 
This feature also enables the engineer to handle long trains in heavy grade work 
with a much greater factor of safety than heretofore and cHminates the need 
for pressure-retaining valves. 

For high-speed trains a high brake-cyHnder pressure available 




Fig. 59. Tj-pe "L" Triple Valve, Showing By-Pass Piston Cap 

Courtesy of Westinphouse A ir Brake Company, 

Wilmerding, Pennsylvania 

for emergency application is imperative, in order to provide a 
maximum braking power when the shortest possible stop is required. 
New Features in "V Type. The following new features are 
incorporated in the new Type ''L" triple valve: 

(1) Quick recharge (of auxiliary reservoirs), making it possible to obtain 
full braking power almost inunediately after a release has been made. 

(2) Quick service, by which a very quick serial service action of tlic brakes 
throughout the train is obtained, similar to that in emergency applications 
but less in degree. 



78 



AlK lU^VKKS 



(3) Oraduatt\l nhasc, which ponnits of ivutly or ontiroly ivloasinjj; the 
brakes on the ontiro train at will. This porniits of tho bost uumIuhI of braking, 




namely, a heavy applit-ation at high s[ieed. gradually reductnl as the speed 
becomes moderate, with just enough brake-cyhnder pressure left to complete 
the stop. 



AIR BRAKES 79 

^i) IJiqh ernerrfjcnci^.ylirul^r [/rtHHure, which greatly infrrea«efi the available 
brukirjK power over that obtainr^l with a fuU-servicf> nyjuction. An with the 
quiek-a/'tion triple valve, the brake-pifx; air is vent^i^J into the brake cyhnder. 
The high ernergency-<;ylinder prf-sHure ib ma^le possible by using air from a 
supplementary resf^rvoir, a res^^rvoir about 2| times the capacity of the aux- 
iliary rewfrvoir in a^idition to that from the auxiliary' rf^sf^n'oir. The usr; of 
the supplementary reservoir alw makes possible the grariuatxid-release feature, 

I'wo illu:~.tratioij-^ of tijc Type "L" triple vahe are given in 
Figs. 58 and o9. Fig. 58 is a side view showing the safety valve in 
I^Iaf-e. Fig. 59 is the opposite side of the valve showing the by-pass 
piston cap. 

V\'^. 00 shows two vertical cross sections of the Type ''L" 
triijle valve with all parts nunrihcrcfl, the names of the parts being 
as follows: 2 valve body; S slide valve; 4 piston; 5 piston ring; 
(J slide-valve spring; 7 graduating valve; 8 emergency-valve piston; 
9 emergency-valve seat; 10 emergency valve; 11 rubber seat for 
emergency valve; 12 check valve spring; IS check- valve case; 
Ui- check-valve case gasket; lo check-valve; 16 emergency-valve 
nut; 17 grarluating-vahe spring; 18 cylinder cap; 19 graduating- 
spring nut; 20 graduating sleeve; 21 graduating spring; 22 cylinder- 
cap gasket; 23 bolt and nut for cylinder cap; 2^ bolt and nut for 
check- vahe case; 25 by-pass piston; 26 by-pass piston ring; 27 
by-pass valve; 28 by-pass-valve seat; 29 by-pass-valve spring; 
■30 by-pass-valve cap; 31 by-pass-piston cap; 32 strainer; 33 safety 
valve; 3/f end cap. 

The Type *'L" triple valve is built in three sizes for use in 
connection with brake cylinders of difterent sizes as follows: Triple 
valve 'T.-1'* for 8- and 10-inch cylinders; ''L-2" for 12- and 14-inch 
cylinders; "I>-3" for 10- and 18-inch cylinders. 

^rhe "L'* triple valve has several recognized positions quite 
similar to those mentioned for other triple \alves already described. 
In explanation of the operation of the valve, reference will be made 
for the sake of clearness to the diagrammatic views shown in Figs. 
01 to 04. In these figures certain parts are referred to by the use 
of abbreviations as follows: B.P. (brake pipe) ; S.R. (supplementary 
reservoir); B.C. (brake cylinder); A.R. (auxiliary reservoir); S.V. 
(safety valve); EX. (exhaust). 

Relea.se and Charfjing Po.ntlon. The valve is illustrated in 
release and charging position in Fig. 01. 



80 



AIR BRAKES 



Air from the brake pipe enters through the passages a, e, g, 
and h, to the face of the triple-valve piston, forcing it to release 
position, thence through feed groove i to chamber R and the aux- 
iliary reservoir. Brake-pipe air in passage a also raises the check 
valve 15, and entering chamber Y flows thence through the ports 




Fig. 61. Type "L" Triple Valve, Showing Release and Charging Position 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

y and j into chamber R and the auxiliary reservoir. This check 
valve then prevents any back flow of air from the auxiliary reservoir 
to the brake pipe. At the same time, port h registers with port x, 
and the air in chamber R also flows through these ports and x' 
and x" into the supplementary reservoir. Both the auxiliary and 
supplementary reservoirs are thus charged at the same time and 



AIR BRAKES 



81 



to the same pressure from the brake pipe through the two different 
channels already mentioned. 

With the parts in the above-mentioned position, air from the 
brake cylinder, entering the triple valve at C\ flows through passage 
r, port 71, large cavity lo in the graduating valve, and ports vi and 
p to the atmosphere, thus releasing the brake. 




Fig. 62. Type "L" Triple Valve, Showing Quick-Service Position 
Courtesy of Wcstinghousc Air Brake Company, Wilmerding, Pennsylvania 

Service Aiyplication. A service reduction in brake-pipe pressure 
reduces the pressure in chamber h and on the face of the trii)lc- 
valve piston below that in the auxiliary reservoir on the opposite 
side of the piston. The higher auxiliary reservoir pressure, there- 
fore, forces the piston in the direction of the lower brake-pipe pres- 
sure, carrying with it the attached graduating valve. The first 
movement of the piston closes the ports J, ?/?, and /»•, Fig. 01, thus 
shutting off communication between the brake pipe and the aux- 



S2 



AIR BRAKES 



iliary and supplementary reservoirs and closing the exhaust passage 
from the brake cylinder to the atmosphere. The same movement 
opens port s and connects ports Q and o in the main slide valve 
tlirough the small cavity in the graduating valve, Fig. G2. 
The spider, or lugs, on the end of the main slide valve, which 
is carried along ^^ith the piston and graduating valve as the reduc- 



■ARi 




Fig. 63. Tj-pe "L" Triple Valve, Showing Full-Sen-ice Position 
Courtesy of Westinghouse Air Brake Company, Wihucrdituj, Pennsylvania 



tion continues, finally brings the parts to quick-service position. 
Service port z in the slide valve registers with the brake-cylinder 
port r in the seat, permitting the air in the auxiliary reservoir to 
flow to the brake cylinder and apply the brakes. At the same time, 
the quick-service ports o and Q, cavity q in the slide valve, and the 
small cavity v in the graduating valve connect passage y, leading 
from the chamber Y in the check-valve case, with passage r' lead- 



AIR BRAKES 83 

ing t<) the brake cylinder. This allows air from the brake pipe to 
lift the check valve and flow through the aUne-named p^^rts to 
the brake cylinder. Thils cr^nstitutes the qukk-fseTvke action of 
the triple valve, in thiat it causes a slight but definite reriuclion in 
break-pipe pressure W:ally at each valve. The amount of air 
veriterl from the brake pijje to the cylinder through the quick-ser\'ice 
j>orts is not gr(;at in amount: fir-^t, because the p^jrts and pa.ssages 
are small; and, second, becaase in the movement of slide valve 3 
to full-senice pfjsition the quick-ser\'ice p^^rt y b restricted as it 
api>roaches this position and Is completely closerl jast before the 
service port z is fully ojxjn. Tlje amount by wtiich the service 
jxjrt is ofx ried def>ends in any given case u[Xjn the rate of reduction 
in break-pif>e pressure as compared with t>iat of the auxiliarv' reser- 
voir. If the former is at first rapid as compared with the latter, 
which would I>e the case with short trairLS, the higher auxiliarj- 
res^ir\'oir pressure moves the jjiston at once to jull-^ercire p^^sition, 
shown in Fig. 63, thus automatically cutting out the quick-ser\'ice 
feature where it is not needed. 

When in jull-service position, the senice p^>rt z is fully open 
and the quick-senice \X)Tt o is closed. This stops the flow of air 
from the brake pi{>e to the brake cylinder and the quick-service 
action ceases. The graduating spring is slightly compressed in the 
full-service position. In any case where the brake-pipe reduction 
is so rapid that the quick-ser\'ice feature is of no advantage, the 
difference of pressure on the two sides of the triple-valve pisUjn 
?>ecomes at the same time sufficient to compress the graduating 
spring and automatically close the quick-service p^jrt. But if 
the brake-pir>e reduction is less rapid or slow, as in the case of long 
trains or m^xlerate-service re^luctiorLS, a partial opening only of 
the service jx^rt is sufficient to preserve a balance between the pres- 
sure on the two sides of the triple-valve piston. The service port 
connecting the auxiliary- reservoir to the brake cyUnder is much 
larger than the quick-service port connecting the brake pipe txj 
the brake cylinder. This serves to effectually prevent an emer- 
gency application I>eing obtained when only a service appfication 
is desired. 

During the time the slide valve 3 remains in quick- or full- 
service position the cavity q connects the brake-cyUnder port / 



84 AIR BRAKES 

with port b leading to the safety valve, which is ordinarily set for 
62 pounds. In event of the brake-cylinder pressure rising to 62 
pounds, the safety valve acts and prevents further pressure increase 
in the brake cylinder. 

Lap Position. After sufficient reduction of brake-pipe pres- 
sure has taken place to apply the brake to the desired amount, 
the flow of air from the auxiliary reservoir to the brake cylinder 
will reduce the pressure on the reservoir side of the triple-valve 
piston slightly below the brake-pipe pressure. The slightly excess 
pressure, together with the slightly compressed graduating spring, 
will move the piston and graduating valve to lap position. In 
this position all ports are blanked by the graduating valve, and the 
air flowing to the brake cylinder w^ill be stopped. The slight differ- 
ence in pressure which caused the piston to move is not sufficient 
to move the slide valve 3 when the piston-stem shoulder comes in 
contact with the slide valve. Therefore, there is no further move- 
ment of triple-valve parts until conditions are changed. 

The lap position of the slide valve 3 is determined by the position 
previous to lap. The graduating valve is the only valve moved 
in obtaining lap position; so if the slide valve is in quick-service or 
full-service position, the lap position obtained will be quick-service 
lap or full-service lap. 

Release and Recharge. When the brake-pipe pressure is in- 
creased to release the brake, the pressure on the brake-pipe side 
of the piston causes the piston to move, and with it the slide valve 
and graduating valve, to the extreme right, as shown in Fig. 61. 

In this position the air in the brake cylinder is exhausted through 
ports r and 7i, the large cavity iv in the graduating valve and port m 
to the exhaust passage p and atmosphere, as previously described. 
INIeanwhile, the auxiliary reservoir is being recharged from the brake 
pipe through the ports y and j and feed groove i. At the same time, 
port X, leading from the supplementary reservoir, is open through 
port k to the auxihary reservoir. The air, which was prevented 
from leaving the supplementary reservoir by movement of the slide 
valve to service position, now flows into the auxiliary reservoir 
and helps to recharge it. 

During the time the slide valve is in release position, the pres- 
sures on the brake pipe and auxiliary reservoir sides of the triple- 



AIR BRAKES 



85 



valve piston are always balanced. This is of importance, as it 
insures a quick response of the brakes to any reduction or increase 
in brake-pij^e pressure irrespective of what operation may have 
occurred immediately preceding. The supplementary reservoir is at 
the same time being re-charged, as has been previously explained. 



— S/?. 



Yar 




Fig. 64. Type "L" Triple \ alvo, Showing l'>inergenry Position 
Courtesy of Westinghouse Air Brake Company, Wilmerdiny, Pennsylvania 

Graduated Release. Suppose that, after the brakes have been 
applied, only sufficient air is permitted to flow into the brake pipe 
to move piston 4 with the slide and graduating valve to release 
position, and the engineer's brake-valve handle is then returned 
to lap position. Then the flow of air from the supplementary 



86 AIR BRAKES 

reservoir through ports x and k to the auxiUary reservoir continuing 
after the rise in break-pipe pressure has ceased will raise the pressure 
on the auxiliary-reservoir side of the triple-valve piston slightly 
above that on the break-pipe side and cause the piston and its 
attached graduating valve to move to the left to graduated release- 
lap position. 

In this position the graduating valve closes the exhaust port 
m, Fig. 61, thus preventing further flow of air from the brake cylinder 
to the atmosphere. It also closes port k — which prevents further 
recharging of the auxiliary reservoir from the supplementary reser- 
voir — and port j and feed groove i, which cuts off the supply of air 
from the brake pipe to the auxiliary reservoir. Thus the brake is 
only partly released and a portion of the air pressure originally 
in the brake cylinder still remains there. In this way the brake 
may be released in a series of steps or graduations. 

Emergency Position. When the brake-pipe pressure is reduced 
suddenly, or its reduction continues to be more rapid than that of 
the auxiliary-reservoir pressure, the piston is forced to the extreme 
left and compresses the graduating spring. The parts are then in 
emergency position, as shown in Fig. 64. In this position air from 
the auxiliary reservoir enters the brake-cylinder passage r through 
the port s in the main slide valve, instead of port z as in service 
application. Port t in the seat is also uncovered by the end of 
the main slide valve, thus admitting air from the auxiliary reservoir 
through port t to the top of the emergency piston. The air pressure 
thus admitted to the top of this piston pushes it down and forces 
the rubber-seated emergency valve from its seat. This allows the 
brake-pipe air in passage a to lift the emergency check valve and 
flow through chambers Y and X to the brake cylinder C in the 
ordinary way. At the same time, port d in the main slide valve 
registers wdth port c in the seat. This allows air from behind the 
by-pass piston to flow through ports c, d, and ?i to / and the brake 
cylinder. As there is no pressure in the brake cylinder at this 
instant, the by-pass piston with its attached by-pass valve is forced 
upward, diagrammatically (or inward, actually) by the auxiliary- 
reservoir pressure acting on the lower (or outer) side of the piston. 
The air in the supplementary reservoir then flows past this valve 
into the passageway leading to the auxiliary reservoir. It thereby 



AIR BRAKES 



87 



adds to the latter the volume of the supplementary reservoir. This 
gives, in effect, an auxiliary-reservoir volume approximately three 
and one-half times the size of the one which supplies air to the 
brake cylinder in service applications. Air from the supplementary 
reservoir continues to flow to the auxiliary reservoir until the pres- 
sure in the latter and that in the brake cylinder have risen nearly 
to that remaining in the supplementary reservoir. Communication 




i" ripe Tap 



Fig. 65. Single-Pressure Retain- 
ing Valve, Open 




Fig. 66. Single-Presi3ure Retaining 
Valve, Closed 



is then closed between the two reservoirs by means of the by-pass 
valve spring and valve. 

In emergency position the communication with the safety valve 
is cut off and the pressure is held until the brake is released. 

MISCELLANEOUS TYPES OF VALVES 

Pressure Retaining Valve. The pressure retaining valve is a 
regular part of all freight car equipment and is furnished with passen- 
ger car equipments only on special order. It is usually fastened on 
the end of the car, by means of lag screws, in a convenient position. 



88 



AIR BRAKES 



and is connected to the triple-valve exhaust port by the retaining- 

valve pipe. Pressure retaining valves are built in two types: namely, 

plain, or single-pressure; and com- 
bined high- and low-pressure. 

The plain, or single-pressure, re- 
taining valve. Figs. 65 and 66, con- 
sists of a plug cock 6 connected to 
the retaining valve pipe at X and 
having two outlets, one to the atmos- 
phere and the other to the retaining 
valve proper. This latter consists of 
a weighted valve 4 normally resting 
on a seat 2 and holding port h closed. 
When the handle 5 of the retaining 
valve is turned down, the groove a 
in the cock key connects port h and 
the outlet c to 
the atmos- 
phere. Conse- 
quently, when 
"turned down" 
the triple-valve 

exhaust is open through tne retaining-valve 

pipe, port h, groove a, and exhaust port c to 

the atmosphere. When the retaining-valve 

handle is ^'turned up" to the horizontal posi- 
tion, Fig. 66, groove a connects port h below 

the cock key with port h above it, so that 

w^hen a release is made, the air exhausting 

from the brake cylinder flows to the retaining 

valve and through port 6, cavity a, and upper 

port h to the weighted valve 4> which it must 

lift in order to flow past valve 4 to the atmos- Fig. 68. High- and Low-Pres- 

-, , —,, . , sure Retaining Valve, 

pnere through the small port a. i he weight showing Three 

. . . „ ^ T Positions 

If. is capable of retaining a pressure of 15 pounds 

in the brake cylinder. As long as the pressure of the air from the 
brake cyhnder is greater than this, it holds the valve 4 from its seat 
and the air exhausts to the atmosphere through port d, which, being 




Fig. 67. High- and Low-Pressure 
Retaining Valve Section 




AIR BRAKES 



89 




Zt 



Fig. 69. Simple Conductor's Valve 



small, makes the release of the brake much slower than when the 
retaining \al\ e is not used. When the pressure has been reduced to 
15 pounds, it is no longer able to hold the weighted \ alve 4 <>^1' its 

seat and the valve then closes and the 
remaining 15 pounds is retained in the 
brake cylinder until the handle 5 is 
turned down. When used on vesti- 
buled passenger cars, the valve is pro- 
vided with an extension handle to per- 
mit of its being conveniently operated 
from the platform. 

High' and Loiv-Pressure Retain- 
ing Valve. Under extreme conditions 
of heavily loaded trains on grades, it 
is often necessary to provide for retain- 
ing more than 15 pounds in the brake 
cylinder. The high- and low-pressure retaining valve, Fig. 67, is 
used for this purpose. This is similar to the valve just described 
except that a cylindrical weight 10, surrounding the usual weighted 
valve 4y is added. W^hen the handle 5 is ''turned down", air from 
the brake cylinder passes freely to the 
atmosphere, as explained, and a lug on 
handle 5 raises the lifting pin 9 and 
the outer weight 10 so that the smaller 
weight 4 alone rests on the valve seat 
and the wear is reduced to a minimum. 
When the handle is ''turned up" to 
a horizontal position, as in the case 
of the plain, or single-pressure, retain- 
ing valve, another lug on the handle 
raises lifting pin 9 and the outer 
weight 10 so that the smaller weight 4- 
alone acts to retain 15 pounds pressure 
in the brake cylinder in the manner Fig. 70. "b-3-a" Conductor'.s Vaive 
already described. 

When it is desired to retain a higher pressure in the brake cylin- 
der, the handle is placed in the intermediate position marked "High 
Pressure", Fig. G8. This permits the lifting pin 9 to drop away 




90 



AIR BRAKES 



from the outer weight 10, Fig. 67, which then rests on the inner 
weight 4 and the air pressure must then Hft both weights, the com- 
bined weight of which is capable of retaining 30 pounds in the brake 
cyHnder before it can escape to the atmosphere. Conditions in 
some sections of the country require relatively lower pressures to be 
retained. To meet this demand, retaining valves are built to retain 




Ta Brake Culirrder 
i P'P^ Top- 



Fig. 71. Westinghouse High-Speed Reducing Valve 

pressures from 10 to 25 pounds. Where it is desired to retain higher 
pressures, they are built as high as 50 pounds. 

Conductor's Valve. The conductor's valve. Fig. 69, is a part of 
all passenger car equipments and is now in common use. Fig. 70 
illustrates the type of valve now being furnished. It is connected 
to a branch pipe leading from the brake pipe and is conveniently 
located inside of the car, so that in case of an emergency or necessity 
it can be reached. Frequently a cord is attached to the handle 



AIR BRAKES 



91 



which runs the entire length of the car and permits of the opening 
of the valve with the least possible delay. The valve most commonly 
used is of the non-self-closing plug-cock t}pe. When the valve is 
opened, it permits air from the 
brake pipe to escape freely to 
the atmosphere, causing a 
quick-action application of all 
brakes in the train. After 
making a stop in this manner, 
the valve must be closed be- 
fore the brake pipe and sys- 
tem can be re-charged and the 
brakes released. 

High=Speed Reducing 
Valve. It has been known 
for a good many years that as 
the speed of the train is in- 
creased, the maximum brake- 
shoe pressure may also be in- 
creased without danger of 
skidding the wheels. That is, 
a train going at a speed of 80 
miles an hour would require a 
much greater brake-shoe pres- 
sure to skid the wheels than a 
train going 5 miles an hour. 
This fact has been taken ad- 
vantage of in the design of 
the high-speed brake equip- 
ment. Instead of carrying a 
brake-pipe pressure of 70 
pounds, a much higher pres- 
sure is used, the usual pres- 
sure being 110 pounds. When 
a full-service application is 
made, about 85 pounds pressure is obtained in the brake cylinder. 
If this pressure were allowed to continue in the brake cylinder until 
the train stopped, there would be danger of skidding the wheels. In 




92 



AIR BRAKES 




order to prevent this, a valve known as the automatic high-speed 
reducing valve is used. The construction of this valve is shown in 

Fig. 71 and Fig. 72 illus- 



trates the application of 
the valve to a car. 

Method of Action. 
When air enters the brake 
cylinder from the auxil- 
iary reservoir, it has free 
access to the reducing 
valve through a pipe at 
C in section B, Fig. 71, 
so that chamber d above 
piston 4 is always sub- 
ject to brake-cylinder 
pressures. Regulating 
spring 11, adjusted by 
nut 12, provides a resist- 

Fig.73. Position of Ports for Release Position ^^^^^ ^^ ^^le doWUWard 

movement of piston 4, 
which is finally stopped 
by spring box 3. Con- 
nected to piston 4 is its 
stem 6, fitted with two 
collars which control the 
movements of slide valve 
8. Slide valve 8 is pro- 
vided with a triangular 
port b in its face, which 
is always in communica- 
tion w^ith chamber d. 
Port a in the slide valve 
seat leads directly to the 
atmosphere through ex- 
haust opening Ex. 

Normal Position. 
Fig. 71^ shows slide valve 8 and its piston 4 in normal positions, 
which are held if brake-cylinder pressure does not exceed 60 pounds. 




Fig. 74. 



Position of Ports, Service Stop, Pressure Exceed- 
ing 60 Pounds in Brake Cylinder 



AIR BRAKES 



93 



Release Position. In release position, Fig. 73, it will be noted 
that port h of slide valve 8 does not register with port a of its seat, 
so that when the brakes are applied they will remain so until released 
in the usual way, unless the brake-cylinder pressure becomes suffi- 
ciently great to overcome the tension of spring 11 and force piston 
4 downward. 

Heavy Service Application. When the brake-cylinder pressure 
begins to exceed GO pounds, in a heavy-service application, the pres- 
sure upon piston 4 moves it downward until port b in the slide valve 
registers with port a in its seat, as shown in Fig. 74, in which posi- 
tion any surplus brake- 



cylinder pressure is 
promptly discharged to 
the atmosphere. The 
spring then raises the 
piston and slide valve to 
their normal positions, 
closing the exhaust port 
and retaining 60 pounds 
pressure in the brake cyl- 
inder. In the operation 
just described, the great- 
est width of port b is 
exposed to port a, and 
these ports are so pro- 
portioned that, in this 
particular position, the 
surplus air is discharged 
from the cylinder full}' as rapidly as it is admitted through the 
service-application port of the triple valve. 

Emergency Application. In an emergency application of the 
brakes, the rapid admission of a large volume of air to the brake 
cylinder raises the pressure more quickly than it can be discharged 
through the service port of the pressure-reducing valve. Under 
these conditions, piston 4 of the high-speed reducing valve. Fig. 75, 
is forced to the lower end of its stroke, in which position the apex 
of triangular port b in the slide valve is brought to register with 
port a, thus restricting the discharge of air from the brake cylinder 




Fig. 75. Position of Ports, Emergency Stop for 
Westinghouse High-Speed Reducing Valve 



94 



AIR BRAKES 



in such a manner that the pressure in the brake cyUnder does not 
become reduced to 60 pounds until the speed of the train has been 
very materially decreased; but the area of the opening of port b 

gradually increases as the reducing 
pressure above piston 4 permits the 
spring to raise the piston and slide 
valve slowly. The rate of the dis- 
charge thus increases as the speed 
of the train decreases, until finally, 
when the brake-cylinder pressure 
has become reduced to 60 pounds, 
port a is closed, and the remainder 
of the brake-cylinder ^pressure is 
retained until released in the usual 
way through the triple valve. 

When an emergency applica- 
tion of the brakes occurs at high 
speeds, there is little danger of w^heel 
sliding, and it will be observed that 
port b is so shaped Jthat brake-cyl- 
inder pressure escapes slowly at such 
time, as already explained; while, 
at lower speeds, where a heavy- 
service application is more likely 
to occur and there is a greater 
tendency toward wheel sliding, the 
base of triangular port b is exposed, 
allowing brake-cylinder pressure to 
reduce quickly. 

Cars not equipped with the 
reducing valve should not be at- 
tached to trains employing the high- 
speed brake equipment unless the 
brake cylinders are equipped with 
a safety valve provided for temporary use in such cases. 

"E=6" Safety Valve. The ''P'-6" safety valve forms an important 
part of several different air-brake equipments. This is especially 
true of the **ET'' locomotive brake equipment. Its form of con- 




Fig. 76. "E-G" Safoty Valve 
Courtrsi/ of Westinf/hotise A ir Brake 
Company, Wihncrdiny, Pennsylvania 



AIR BRAKES 



95 



struction and operation is clearly shown in Fig. 7G, which is a vertical 
section of the valve. Its construction is such as to cause it to close 
quickly with a x>op action, which insures a firm seating. Valve 4 i^ 
held to its seat by the compression of spring 6. When the pressure 




Fig. 77. Hose Protecting Coupling, Showing Flexible Head 
Courtesjj of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

below valve .4 overcomes the spring pressure above, it rises until 
valve stem 5 is stopped by cap nut 3. The air in discharging passes 
around valve 4 and out at ports in the body 2, one of which is shown. 
As the pressure drops, valve 4 moves downward slightly and partly 
closes the discharge ports in the body 
2. Air then flows to the spring cham- 
ber and assists the spring in closing 
the valve, thus assisting in the ''pop" 
action referred to above. 

Two of the important brake-pipe 
fittings are shown in Figs. 77 and 78, 
Fig. 77 showing the scheme used in 
joining the flexible hose between cars. 
When uncoupled, the hose should 
always be attached to the dummy 
coupling to keep the hose from being 
injured by swinging and to prevent 
cinders and dirt from getting into the 
brake pipe. The hose should always be parted by hand and not i)ulled 
apart by the separation of the cars. Fig. 78 illustrates the type of 
centrifugal dirt collector. It is placed in the branch pipe leading 
to the triple valve. The centrifugal dirt collector replaces the older 




Fig. 78. Centrifugal Dirt Collector 

Courtesy of Westinqhouse Air Brake 

ComiMny, Wilmerding, Pennsylvania 



96 AIR BRAKES 

form of strainer which has been common for a number of years. It 
can be cleaned by removing the plug at the bottom. 

BRAKES AND FOUNDATION BRAKE GEAR 

General Requirements. The foundation brake gear includes all 
levers, rods, beams, pins, etc., which serve to transmit the braking 
force from the piston of the brake cyHnder to the brake shoes. It is 
important that all longitudinal rods should be parallel with the 
center line of the car, when the brakes are fully applied. The brake 
beams should be hung in such a manner that they will always be the 

^^ Mand Brake al Cne End 

Inside Munq 

-CD /C LJ 



n. 



f 



" 



/ZZL 



Culsrde Hong 

^ C ZZZ7 



f=^F-l 



B 

o 



n 



Hand Brake at Both Ends 
Inside Hung 

^ c u 



1=^^-^ 



I — 1 



Cuhide Hong 

-CD p 1 — 7 



D 



■I 



Fig. 79. Foundation Brake-Gear Systems Adopted by Master Car Builders' Association 

same distance above the rail, the reason being that this practice 
reduces the chance for flat wheels, since the piston travel is not 
affected by the loading or unloading of the car. The rods and levers 
should be designed so that they will move in the same direction 
when the brakes are applied by hand as when by air. The levers 
should stand approximately at right angles to the rods, when the 
brakes are set. 

A number of different systems of rods and levers have been 
used by different railroad companies, with varying degrees of suc- 
cess. The systems adopted by the INIaster Car Builders' Associ- 
ation are diagrammatically shown in Fig. 79. , The four cases shown 
represent two general systems— those where the brake shoes are hung 
inside, between the truck wheels; and those where they are hung 



AIR BRAKES 



97 



outside. Freight cars are gener- 
ally fitted with the brake shoes 
hung inside, while the passenger 
cars usually have the brake shoes 
hung outside. In the first two 
cases (.1 and B),t\\e brake can 
be applied by hand from only 
one end of the car; while in the 
other two cases (C and JJ), the 
brake can be operated by hand 
from either end. In applying 
the brake by hand in any case, 
the coil spring in the brake cyl- 
inder offers no resistance, since 
the push rod has no pin con- 
nection to the piston rod. The 
piston rod of the brake cylinder 
is hollow. When the brake is 
operated by hand, the push rod 
slides outward in the hollow rod 
without moving the piston. A 
detailed description of the oper- 
ation of the four cases shown is 
not thought necessary. One or 
two points, however, might 
assist to a clearer understanding 
of them. The lower end of the 
lever 1 in A and B is fixed at 0. 
The lower end of the lever 1 in 
C and D is held by a stop at 
and cannot move to the left, but 
is free to move to the right when 
the brake is operated by hand 
from the right-hand end of the 
car. The lever 2 in all four 
cases has no fixed points. In 
all cases, the arrangement is 
such that no brake shoe will 




bt 

a 



c 
o 



O 



PQ 



12 

C 



<A 



O 



bO 

(2 



:>fPOJ 9]5l 



9S 



AIR BRAKES 




TF = 



F = :^z^; l=a-\-b'. 



FX a 


b 

Wx b 


a 
W X b 


F 

F X a 



Wx I 
a = ;:^ — ; or, a = 



^ ^nr^' °''^ 



F + W* 

Fx I 
F+W 



FULCRUM BETWEEN APPLIED AND DELIVERED FORCES 




TF = 



F X a 



^ - ; a = b + d: 

a ' 

^ Wxb Wxd 
a = — = — ; or, a ^ — _ 



F 



W- F' 



W ' ' W- F 



DELIVERED FORCE BETWEEN FULCRUM AND APPLIED FORCE 




w= 



Fx a 



r = ; b = a + d: 

a 

W Xb W - d 

a = — - — ; or, a = ; 

F ' ' F -W 

, F X a , F X d 



APPLIED FORCE BETWEEN FULCRUIM AND DELIVERED FORCE 
Fig. 81. Illustrating Application of Principle of Moments to Levers in Brake Systems 



AIR BRAKES 



99 



press against its wheel with any 
great force until all brake shoes are 
held firmly against their respective 
wheels, and all shoes press against 
the wheels with an equal force. 
Fig. 80, with the various parts 
named, shows the application of case 
A of Fig. 79 to a freight car. 

Leverage. It is a well-known 
principle in Mechanics, that the 
greater the weight on a car wheel, 
the greater the brake-shoe pressure 
necessary to cause it to slide or 
skid on the track. For this reason, 
in designing the brake levers, rods, 
etc., for a freight car, the light or 
unloaded weight of the car is the 
basis of all calculations. If the 
loaded weight of the car were used 
in the calculations, the proportions 
would be such that if the brakes 
were applied when the car was un- 
loaded the wheels would slide. In 
order to prevent as far as possible 
chances arising of having flat spots 
worn on the wheels, due to wheels 
sliding on the track, the following 
percentages of light weights on the 
wheels are usually, but not always, 
employed in determining the brake- 
shoe pressure : 

Passenger cars 90 per cent 

Freight cars 70 per cent 

Tenders 100 per cent 

Locomotive drivers .... 75 per cent (of 

weight on 
(h'ivers) 

Locomotive truck 75 per cent (of 

weight on 
truck) 





;<5/ 




.g^ 



m 



A 




.,6/- 



\9 



V^" 




o 



u 

c 



U 



O 



G 



J3 

m 



^ 



100 AIR BRAKES 

It is frequently found necessary to change these percentages in 
order to meet special conditions which arise. 

In calculating the brake-shoe pressure of any car the following 
three things must be known: First, the diameter of the brake cyl- 
inder and its maximum pressure; second, the sizes and positions of 
all levers in the system; and third, a working knowledge of the 
theorem of moments as used in Mechanics. 

The principle or theorem of moments may briefly be stated as 
follows : The product of the force applied at one pin and its perpen- 
dicular distance from the fulcrum pin is equal to the product of the 
force delivered at the other pin and its perpendicular distance from the 
fulcrum pin. This principle has been applied to the three different 
classes of levers, and the forces and distances worked out, Fig. 81. 
The chief difficulty the amateur experiences is in locating the fulcrum 
pin. In A, B, and C, Fig. 81, the fulcrum pin is located at 0, the 
force applied is F, and the force delivered is IF. In any case, if the 
pull F on the lever is known, the brake-shoe pressure W can be 
determined. 

Fig. 82 represents diagrammatically the scheme of levers and 
rods commonly used on freight cars. All distances of rods from the 
center line of the car are taken when the levers are at right angles 
to it. The brake cylinder on a certain freight car, taken as an 
illustration, is 8 inches in diameter, and has an area of about 50 square 
inches. If the maximum brake-cylinder pressure in emergency 
applications is 60 pounds, the total pressure delivered to the push 
rod would be 50X60, or 3000 pounds. This 3000 pounds is trans- 
mitted to the lever E at the pin 1 . The lever E is of the class shown 
in B, Fig. 81, and its fulcrum is at the pin 3. Applying the formula 
gives 4500 pounds delivered at the pin 2. This 4500 pounds is trans- 
mitted to the lever F, which is of the class shown in C, Fig. 81, and 
its fulcrum is at the pin 6. Applying the formula gives 1500 pounds 
dehvered at the pin 4. This 1500 pounds is transmitted to the 
lever A, which is of the class shown in A, Fig. 81, and its fulcrum is 
at the pin 9. Applying the formula gives 6000 pounds dehvered to 
the brake beam at the pin 8. In a similar manner the other brake- 
beam pressures can be determined. In the figure, the calculation 
has been carried through for both service and emergency appli- 
cations. 



AIR BRAKES 



101 



It is seen that 6000 pounds is transmitted to the middle of each 
of the four brake beams. Each brake shoe will then receive a pres- 
sure of 3000 i)()unds. Since there are eight wheels, the total braking 
pressure will be 8X3000, or 24,000 pounds. This total braking pres- 
sure must not exceed 70 per cent of the unloaded weight of the car. 




Fig. 83. Automatic Slack-Adjuster 

Automatic Slack=Adjuster. Full braking pressure will be 
secured as long as the maximum allowable brake-cylinder pressure 
can be maintained. Since the brake-cylinder pressure depends 
upon the length of stroke of the piston, it follows that the stroke of 




Fig. 84. Part Sectional View of Automatic Slack- Adjuster 

the piston should be kept as nearly constant as possible. The 
greater the stroke, the less the pressure. The stroke of the piston 
should be kept at about 8 inches. As the brake shoes and various 
connections wear, the stroke of the piston is increased, and the pres- 



102 



AIR BRAKES 




Fig. 85. Outside Equalized Driver-Brake for Locomotives 




Hanger Pi n 

Com Screw Pin 
Com Screw 




Upper Cross 
Bracket ' 



Lower Cross Bracket 
5hoe Hang€> 



End View 



Shoe Holder 
Tie Rod Corn Screw Pin 

Side View 



Fig. 86. Cam Driver-Brake for Locomotives 



AIR BRAKES 



103 



sure with which the shoes are forced against the wheels is decreased. 
In order to compensate for this wear, some means must be provided 
for taking up the slack. This ^is done in one of two ways — by 
changing the fulcrnm pin of the dead lever (see Fig. 80) or by using 
the automatic slack-adjuster. The first method of adjustment is 
the one most commonly used and is necessarily very coarsely graded. 
The automatic slack-adjuster, when used at all, is usually fitted to 
the passenger car equipment. 

The automatic slack-adjuster, Figs. 83 and 84, is manufactured 
by the Westinghouse Air Brake Company. The purpose of the 




lOi: i;,ro--9--o-iF 
=r^1iil III 







Fig. 87. Locomotive Truck Brake 



apparatus is to maintam a constant, predetermined piston travel. 
The brake-cylinder piston acts as a valve to control the admission 
and release of air to pipe B through port A. Whenever the stroke 
of the brake-cylinder piston is so great that port A is passed by the 
piston, air from the cylinder enters port A into pipe B and enters 
cylinder C, which is shown in section in Fig. 84. The air entering 
the small cylinder acts on piston 1, forcing it to the left, compressing 
spring 2, and causing the small pawl 3 to engage the ratchet wheel 
4. When the brake is released, the brake-cylinder piston returns, 



104 AIR BRAKES 

and air in the small cylinder C escapes to the atmosphere through 
pipe B and port A, thus permitting spring ^ to force piston 1 to its 
normal position. In so doing, pawl 3 turns the ratchet wheel 4 on 
screw 5, and thereby draws the fulcrum end of lever 6 slightly nearer 
the slack-adjuster cylinder C, Each operation of piston 1, as just 
described, reduces the brake-cylinder piston travel about ^ of an 
inch. When piston 1 is in its normal position, the outer end of 
pawl 3 is lifted, permitting screw 5 to be turned by hand. 

Locomotive Driver Brakes. The brakes are applied to the 
drivers of a locomotive in two general ways — by the outside equalized 
system, Fig. 85, and by cams, Fig. 86. The former scheme has 
practically replaced the latter, because of its simple design and 
adjustment. In the system. Fig. 85, the levers are proportioned so 
that each wheel receives the same braking pressure. If the brake 
cylinders are each 14 inches in diameter and the cylinder pressure 
is 50 pounds, the pressure delivered at pin A is about 7650 
pounds, while that on each wheel is 10,200 pounds. These values 
vary for different locomotives. The stroke of the piston is regulated 
by the adjustment mechanism at B. 

The action of the cam-driver brake is shown in Fig. 86. When 
air is admitted to the brake cylinder, the piston is forced downward. 
This action pushes down the crosshead cams, w^hich force the brake 
shoes against the drivers. The piston travel is controlled by adjust- 
ing the cam nut on each cam. 

Locomotive Truck Brakes. In certain types of locomotives, a 
considerable proportion of the weight of the locomotive is carried 
on the truck. It follows, that in order to develop the full braking 
power of the locomotive, a well-designed truck brake should be 
provided. The type of brake shown in Fig. 87 is now quite com- 
mon. It is fitted with an automatic slack-adjuster, but this feature 
is not so important here as on the car equipment. 



AIR BRAKES 

PART II 



MODERN BRAKE EQUIPMENT 

FUNDAMENTAL TYPES 

High=Speed Brake Equipment. The high-speed brake equip- 
ment, Fig. 88, is a modification of the quick-action brake and can be 
used in passenger service. Tlie parts not found on the onUnary 
equipment are as follows: Type "E" safety valve, high-speed 
reducing valve, reversing cock, feed-valve bracket, and an additional 
feed valve. 

Action of Reversing Cock. The locomotive equipment may be 
changed from the quick-action to the high-speed brake by simply 
turning the reversing-cock handle. When this handle is in the ])osi- 
tion opposite to that shown in Fig. 88, the 7()-pound feed valve is in 
service, so that the locomotive is ready to operate the ordinary 
quick-action brake; when the brake-valve handle is in running posi- 
tion, 70 pounds pressure is carried in the brake pipe, and the com- 
pressor will slow^ down when main-reservoir pressure reaches 90 
pounds. If, however, the brake-valve handle is in lap, service, or 
emergency-application position, main-reservoir pressure is cut ofT 
from the excess-pressure head, and the compressor will continue to 
operate until the main-reservoir pressure reaches the limit set by the 
maximum pressure head, to insure available pressure promptly to 
release and re-charge the brakes on long and heavy trains. 

If the reversing-cock handle be turned to the position shown, 
the 110-pound feed valve will become operative, giving 110 pounds 
brake-pipe pressure, which results in a corresponding increase in 
main-reservoir pressure depending upon the adjustment of the 
maximum pressure head of the governor. 

Principles Involved. The principles involved in the high-speed 
brake are (a) the friction between the brake shoe and the wheel, 



106 



AIR BRAKES 




"3 

W 
a> 

W 



02 



w 



3 
O 



^ 



(si 



AIR BRAKES 



107 



that tends to stop the rotation, becomes less as the rapidity of rota- 
tion of the wheel increases, and (b) the adhesion between the wheel 
and rail remains practically constant regardless of the speed. It 
will thus be seen that, at high speeds, a greater brake-cylinder 
pressure, with corresponding increase of the brake-shoe pressure, 
can be used without danger of sliding wheels; but, in such a case, 
it is necessary to provide means for reducing this high-cylinder 
pressure as the speed of the train is decreased. This is accomplished 
by the automatic reducing valve, which has previously been 
explained. 

Cars not fitted with reducing valves should not be attached to 
trains using the high-speed brake unless the brake cylinders are 

































































6C 












































































































^ 














































rc 








































% 






^ 
























5; 






























































1.- 










































































































t3 


















^- 














45 




^ 1 


— 


■■ 


— 




- 














— 






■- 






Gi 


HCI 


3, 


Id 


on 


B. 


■ah 
hi 


e 
































t/h 









Fig. 89. 



^oo 400 600 eoo icco i^co it-cc leoo leoo ^oco c'^co ^^oo peco ^eco jcoo 
Length cf 5lopin Feet 

Diagram Showing Minimum Length of Stop for Train of Engine and 
Six Coaches with Quick-Action and High-Speed Brakes 



fitted with the Type "E" safety valve provided for temporary use. 
Fig. 89 illustrates graphically the saving in distance in stopping a 
train fitted with the high-speed brake equipment. 

Double=Pressure Control or Schedule "U". The differences 
between Schedule ''U" and high-speed equipments are that no 
additional parts are used on cars with Schedule ''U". The Type 
"E" safety valve takes the place of the high-speed reducing valve 
in the locomotive and tender equipment, and plain trii)le valves 
are used on both the locomotive and tender. The equipment is 
shown in Fig. 90. The few simple appliances afford the means 



108 



AIR BRAKES 



whereby the engineer can change the brake-pipe and main-reservoir 
pressure from one predetermined standard to another at will. 



pUOOdg U95Mpq^ 9J10AJ959}J pUODSg 
^ ICJtJ Ud9Mpq 'JlOAJdS9y iSJlJ^ 

duinj^ u33Mpq adijjo }J9J l^oqu- 




The equipment is particularly adapted for use upon heavy 
grades where ''empties" are hauled up the grade and ''loads" down. 



AIR BRAKES 



ino 



The 70-poiind brake-pipe pressure provides for a proper control of 
the empty cars, and requires less work from the compressor, while 
the 90-pound pressure makes it possible to obtain higher brake- 
cylinder pressures to compensate for the increased weight to be 
controlled when the cars are loaded. The loaded weight of the car 
is still, however, sufficiently in excess of the maximum braking 
power obtainable to insure an ample margin against wheel sliding. 

"LN'* Passenger=Car Brake Equipment. The demand for a 
more efficient brake equipment for passenger service, to meet the 
new conditions of heavier trains, faster speeds, and more frequent 
service, resulted in the development of the "LN'* equipment. A 
diagram illustrating the arrangement of piping and location and 



-Brake Cijhnder 




Fig. 91. Westinghouse Piping Diagram for "LN" Passenger Brake Equipment 



names of all parts is shown in Fig. 91. The principles underlying 
the action of the parts have already been presented under the dis- 
cussion of the Type ''L" triple valve. 

Specifications. The equipment is made up of the following 
parts: 

(1) A triple valve, Type "L", which has connections through the brakc- 
cyhnder head to the brake-pipe branch pipe, the auxihary reservoir, and the 
supplementary reservoir. It operates automatically in response to an increase 
or decrease in brake-pipe pressure, as previously described. 

(2) The TijiJe "E" safety valve is attached directly to the Type "L" triple 
valve and thus becomes an important feature of the "LN" equipment, since in 
service applications it prevents any excess brake-cylinder'pressure and in emer- 
gency applications it is cut out entirely. 

(3) A brake eyliiidcr, with a piston and rod which operates in the usual 

way. 

(4) Reservoirs, of which there is one auxiliary and u.sually one supple- 
mentary, for the purpose of storing air for use in applying the brakes. When 



no AIR BRAKES 

desii'able or more convenient, however, two supplementary reservoirs of the 
proper size may be used. 

(5) A centrifugal dirt collector is connected in the branch pipe between the 
brake pipe and triple valve as near the triple valve as circumstances will permit. 

(6) A branch-pipe air strainer is inserted in the branch pipe close to the 
triple-valve connection on the brake-cylinder head for further protection to the 
triple valve. 

(7) A conductor's valve placed inside each car by means of which the 
brakes may be applied by the conductor in case of accident or emergency. 

(8) A branch-pipe tee, various cut-out cocks, angle cocks, hose couplings, 
dummy couplings, etc., the location and uses of which will be readily understood 
by reference to Fig. 91. 

(9) An automatic slack-adjuster, which is not a fundamental part of the 
equipment, but recommended for use. 

The high emergency-cyUnder pressure with the graduated 
release feature, as explained under the discussion of the ''L" triple 
valve, makes it possible to use the equipment as a high-speed brake 
when carrying 90 pounds brake-pipe pressure, and obtain better 
results than when using 110 pounds pressure with the old standard 
equipment in steam-road service. If, then, a more powerful brake 
is desired, it can be obtained by simply increasing the brake-pipe 
pressure. 

> No. 6 "ET" LOCOMOTIVE BRAKE EQUIPMENT 

It has been shown that a single modern locomotive possessed 
a possible braking power of one-tenth of a 50-car freight train, one- 
eighth of a 12-car Pullman train, one-fourth of a 10-car passenger 
train, and one-third of a 6-car passenger train. These figures would 
indicate that the locomotive brake equipment should be developed 
to the highest degree. The first step taken in this direction was 
the development of the combined automatic and straight-air equip- 
ment for locomotives. This system was greatly simplified and 
improved by the more recent development of the so-called ^^ET" 
locomotive brake equipment. 

Functions and Advantages. The No. 6 ''ET" (engine and ten- 
der) equipment possesses all the functions which are now required 
in locomotive brake service; it can be applied to any locomotive 
without change or modification of any of its parts. The locomotive 
so equipped may be used in an}^ kind of service, such as high-speed 
passenger, double-pressure control, ordinary passenger or freight, or 



AIR BRAKES 111 

switching service, without change or adjustment of the brake appa- 
ratus. Its important advantages are as follows: 

The locomotive brakes may be used with or independently of the train 
brakes and this without regard to the position of the locomotive in the train. 

They may be applied with any desired pressure between the minimum 
and the maximum, and this pressure will be automatically maintained in the 
locomotive brake cylinders regardless of leakage from them and of variation in 
piston travel, undesirable though these defects are, until released by the brake 
valve. 

They can be graduated on or off with cither the automatic or the inde- 
pendent brake valves; hence, in all kinds of service the train may be handled 
without shock or danger of parting, and in passenger service smooth, accurate 
stops can be made with greater ease than was heretofore possible. 

Arrangement of Piping, Etc. The general arrangement of 
piping, etc., is shown diagrammatically in Fig. 92. The names of 
the various parts composing the equipment are : 

(a) The air compressor to compress the air. The main reservoirs in which to 
store and cool the air and collect water and dirt. 

(b) A duplex compressor governor to control the compressor when the pressures 
for which it is regulated are obtained. 

(c) A distributing valve, and small double-chamber reservoir to which it is 
attached, placed on the locomotive to perform the functions of triple valves, 
auxiliary reservoirs, double check valves, high-speed reducing valves, etc. 

(d) Two brake valves — the automatic to operate the locomotive and train brakes, 
and the independent to operate the locomotive brakes only. 

(e) A feed valve to regulate the brake-pipe pressure. 

(f) A reducing valve to reduce the pressure for the independent brake valve and 
for the air-signal system when used. 

(g) Two duplex air gages — one, to indicate equalizing-reservoir and main- 
reservoir pressures; the other, to indicate brake-pipe and locomotive brake- 
cylinder pressures. 

(h) Driver, tender, and truck brake cylinders, cut-out cocks, air strainers, hose 
couplings, fittings, etc., incidental to the piping, for purposes readily under- 
stood. 

Names of Pipes. In order to simplify the description of the 
different parts of the equipment, the following names of pipes are 
given which are shown in Fig. 92 : 

Discharge Pipe: Connects the air compressor to the first main reservoir. 

Connecting Pipe: Connects the two main reservoirs. 

Main Reservoir Pipe: Connects the second main reservoir to the automatic 

brake valve, distributing valve, feed valve, reducing valve, and compressor 

governor. 
Feed Valve Pipe: Connects the feed valve to the automatic brake valve. 
Excess-Pressure Pipe: Connects the feed-valve pipe to the upper connect' on 

of the excess-pressure head of the compressor governor. 



AIR BRAKES 113 

Excess-Prcfisure Operating Pipe: Connects the automat io brake valve to the 

lower connection of the excess-pressure head of the compressor governor. 
Reducing Volve Pipe: Connects the reducing valve to the independent brake 

valve, and to the signal system, when used. 
Brake Pipe: Connects the automatic brake valve with the distributing valve 

and all triple valves on the cars in the train. 
Brake-Cylinder Pipe: Connects the distributing valve with the driver, tender, 

and truck-brake cylinders. 
Applicalion Cylinder Pipe: Connects the application cylinder of the distributing 

valve to the independent and automatic brake valves. 
Distributing Valve Release Pipe: Connects the application-cylinder exhaust 

port of the distributing valve to the automatic brake valve through the 

independent brake valve. 

In some installations the automatic brake valve is provided 
with a pipe bracket to which the feed valve is directly attached, 
thus eliminating the feed- valve pipe and the excess-pressure pipe. 

Manipulation of Equipment. Positions of Automatic and Inde- 
pendent Brake Valves. The automatic brake valve has six fixed 
positions for its handle — release, running, holding, lap, service, and 
emergency; while the independent brake valve has but five — release, 
running, lap, sloic-application, and quick-application. 

General Directions. The following directions for the manipu- 
lation of the equipment are abbreviated from that furnished by the 
manufacturers and ai)plies to modern equipment. They are not 
intended to apply rigidly to all individual cases or conditions: 

When not in use, carry the handles of both brake valves in running position. 

To apply the brakes in service, move the handle of the automatic brake 
valve to the service position, making the required brake-pipe reduction, then 
back to lap position, which is the one for holding all the brakes applied. 

To make a smooth and accurate two-application passenger stop, make the 
first application sufficiently heavy to bring the s])eed of the train down to about 
15 miles per hour at a convenient distance from the stopping point, then release 
as explained in the following paragraph and re-apply as required to make the 
desired stop, the final release be^ng made as explained below. 

Passenger Service. In making the first release of a two-application stop, 
the brake-valve handle should be moved to release position and then quickly 
back to running position, where it should be allowed to remain for an instant — 
first, to permit the pressures in the equalizing reservoir and brake pipe to equalize; 
and second, to release part of the driver brake-cyhnder pressure — then moved to 
lap position and from there to service position, as required. In i)ass(^nger service, 
the time the handh^ is in release position should be only momentary; but the 
time in running position should be governed by the conditions existing for each 
particular case, such as the length of train, kind of reduction made, time avail- 
able, and so on. 



114 AIR BRAKES 

In making the final release of a two-application stop, with short trains, 
release shortly before coming to a standstill by moving the handle to release 
position and immediately back to running position, and leave it there. With 
long trains, the brakes should, as a rule, be held applied until the train stops. 

The release after a one-application stop should be made in the same man- 
ner as the final release of a two-application stop. 

Freight Service. Under present conditions it is, as a rule, safest to come to 
a stop before releasing the brakes on a freight train, especially a long one, rather 
than attempt to release at low speed. However, if conditions — for example, 
a short train, or a train equipped with Type "K" triple valves — permit of the 
release while in motion, the brake-valve handle should be moved to release 
position and held there long enough to move as many of the triple valves to 
release position as possible without unduly overcharging the head end of the 
train — the time in release position should be governed by the length of train, 
amount of reduction made, etc. — then returned to running position to release 
the locomotive brakes and complete the recharging of the auxiliary reservoirs. 
A few seconds after such a release, particularly on long trains, it is necessary to 
again move the handle to release position and quickly back to running position 
to "kick off" any brakes at the head end of the train that may have re-applied 
due to their auxiliary reservoirs having been slightly overcharged. 

Holding Locomotive Brakes Applied. If, when releasing, it is desired to 
hold the locomotive brakes applied after the other brakes release, move the 
handle from release back to holding instead of running position, then release the 
locomotive brakes fully by moving the handle to running position and leaving it 
there, or graduate them off, as circumstances require, by short, successive move- 
ments between holding and running positions. 

Emergency Application. To apply the brakes in emergency, move the 
handle of the automatic brake valve quickly to emergency position and leave it 
there until the train stops and the danger is past. 

When using the independent brake only, the handle of the automatic brake 
valve should be carried in running position. The independent application may 
be released by moving the independent brake-valve handle to running position. 
Release position is for use only when the automatic brake-valve handle is not 
in running position. 

While handling long trains of cars, in road or switching service, the inde- 
pendent brake should be operated with care to prevent damage to cars and lading, 
caused by running the slack in or out too hard. In cases of emergency arising 
while the independent brake is applied, apply the automatic brake instantly. The 
safety valve will restrict the brake-cylinder pressure to the proper maximum. 

Heavy Grade Service. The brakes on the locomotive and on the train may 
be alternated in heavy grade service w^here conditions — such as short, steep 
grades or where grade is heavy and straight for short distance — require, to 
prevent overheating of driving-wheel tires and to assist the pressure-retaining 
valves in holding the train while the auxiliary reservoirs are being re-charged. 
This is done by keeping the locomotive brakes released by use of the independent 
brake valve when the train brakes are applied, and applying the locomotive 
brakes just before the train brakes are released, and then releasing the loco- 
motive brakes after the train brakes are re-applied. Care and judgment should 
be exercised in the use of driver brakes on grades to prevent overheating of tires. 



AIR BRAKES Wn 

Release Position of Independent Brake Valve. When all brakes are applied 
automatically, to graduate off or entirely release the locomotive l)rakes only, use 
release position of the independent brake valve. 

The red hand of gage No. 2, Fig. 92, will show at all times the i)r(\ssur(' 
in the locomotive brake cylinders, and this hand should be watched in brake 
manipulation. 

Release i)osition of the independent brake valve will release the locomotive 
brakes under any and all conditions. 

Use of Automatic Brake Valve for Holding and Grade Work. The auto- 
matic brakes should never be used to hold a locomotive or a train while standing 
even where the locomotive is not detached, for longer than ten minutes, and not 
for such time if the grade is very steep or the condition of the brakes is not good. 
The safest method is to hold with hand brakes only and keep the auxiliary 
reservoirs fully charged so as to guard against a start from brakes leaking off 
and to be ready to obtain any part of full braking power immediately on starting. 

The independent brake is a very important safety feature in this connec- 
tion, as it will hold a locomotive with a leaky thi'ottle or quite a heavy train on 
a fairly steep grade if, as the automatic brakes are released, the slack is pre- 
vented from running in or out — depending on the tendency of the grade — and 
giving the locomotive a start. To illustrate: The best method to make a stop 
on a descending grade is to apply the independent brake heavily as the stop is 
being completed, thus bunching the train solidly; then, when stopped, place and 
leave the handle of the independent brake valve in application position; then 
release the automatic brakes and keep them charged. Should the independent 
brake be unable to prevent the train from starting, the automatic brakes will 
become sufficiently recharged to make an immediate stop; in such an event 
enough hand brakes should at once be applied as are necessary to hold the train. 
Many runaways and some serious wTecks have resulted through failure to com- 
ply with the foregoing instructions. 

When leaving the engine, while doing work about it, or when it is standing 
at a coal chute or water plug, always leave the independent brake-valve handle 
in application position. 

After Emergency Application not Controlled by Engineer. After an 
emergency application of the brakes, while running over the road, due to any 
cause* other than intended by the operating engineer himself: 

(1) In passenger service, move the brake-valve handle to emergency 
position at once and leave it there until the train stops. 

(2) In freight service, move the brake-valve handle to lap position and 
let it remain there until the train stops. 

This is to prevent loss of main-reservoir pressure and insure the brakes 
remaining applied until released by the engineer in charge of the train. After 
the train stops, the cause of the application should be located and remedied 
before proceeding. 

More than One Locomotive on Train. W^here there are two or more loco- 
motives in a train, the instructions already given remain unchanged so far as the 
leading locomotive, or the locomotive from which the brakes are being operated, 
is concerned. On all other locomotives in the train, however, the double-heading 
cock under the automatic brake valve must be closed and the automatic and 
independent brake-valve handles carried in running position. 



116 



AIR BRAKES 



Many of the parts composing the No. 6 '^ET" equipment are 
the same as used in connection with other equipments and have 
already been explained. These parts include the following: the 
"H-6" automatic brake valve, the ''S-6" independent brake valve, 
the "B-6" feed valve, the ''C-6" reducing valve, the ''E-6" safety 
valve, the Type "SF" compressor governor, the air compressor, 
etc. The new features are the different pipes and connections, and 
the distributing valve and double-chamber reservoir. 



DISTRIBUTING VALVE AND DOUBLE=CHAMBER RESERVOIR 

General Method of Operation. Fig. 93 illustrates diagrammat- 
ically the essential features of the distributing valve and the double- 
chamber reservoir. In- 

'To Main Reservoir 



Ci^ Under 




stead of a triple valve 
and auxiliary reservoir 
for each of the engine 
and tender equipments, 
the distributing valve is 
made to supply all brake 
cylinders. The distribut- 
ing valve is made up of 
two portions called the 
^'equalizing portion" and 
the ^'application por- 
tion". The valve is con- 
nected to a double-cham- 
ber reservoir, the two 
chambers being called, 
respectively, the ''pres- 
sure chamber" and the 
"application chamber". 
For various reasons the 
distributing valve and 
double-chamber reservoir 
are combined in one de- 
vice. Figs. 94 and 95. 
The distributing valve is the most important feature of the 
"ET" equipment. As shown by Figs. 94, 95, and 96, it has five 



Fig. 93. Diagrammatic View of Essential Parts of 
Westingtiouse Distributing Valve and Double- 
Chamber Reservoir 



AIR BRAKES 



117 





Fig. 94. No. Distributing Valve and Double-Chamber Reservoir. 
MR, Main-Reservoir Pipe; 4, Distributor Valve Release Pipe; ;^, Appli- 
cation-Cylinder Pipe; CYLS, Brake-Cylinder Pipe; BP, Brake Pipe 




Fig. 95. No. G Distributing Valve and Double-Chamber Reservoir, with Pressure 

Chamber Cut Away 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 



118 



AIR BRAKES 



pipe connections. Fig. 96 is a vertical section of the actual valve. 
For the sake of clearness, the distributing vahe together with the 
double-pressure chamber may be considered as a miniature brake 
set, consisting of the equalizing portion representing the triple 
valve; the pressure chamber, the auxiliary reservoir; and the appli- 
cation portion alwavs having practically the same pressure in its 



mt: 



k-<jnSL 




Fig. 96. Section of No. 6 Distributing Valve 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

cylinder as that in the brake cylinders. The equalizing portion and 
pressure chamber are used in automatic applications only; reduc- 
tions of brake-pipe pressure cause the equalizing valve to connect 
the pressure chamber to the application chamber and cylinder, 
allowing air to flow from the former to the latter. The upper slide 
valve, connected to the piston rod of the application portion, admits 
air to the brake cylinders and is called the "application valve", 
while the lower one releases the air from the brake cylinders and is 



AIR BRAKES 



no 



called the ''exhaust valve". As the air admitted to the brake cyl- 
inders comes directly from the main reservoirs, the sui)ply is prac- 
tically unlimited. Any pressure in the application cylinder will 
force the application piston to close the exhaust valve, open the 
application valve, and admit air from the main reservoirs to the 




Fig. 97. Release Position, Automatic or Independent Connections for 
Distributing Valve 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Peimsylvania 

locomotive brake cylinders until their pressure equals or slightly 
exceeds that in the application cylinder; whereupon the application 
piston and valve will be returned to lap position, closing the appli- 
cation valve. Also any variation of application-cylinder pressure 
will be exactly duplicated in the locomotive brake cylinders, and the 
resulting pressure maintained regardless of any brake-cylinder 



120 AIR BRAKES 

leakage. The operation of this locomotive brake, therefore, depends 
upon the admitting of air to and the releasing of air from the appli- 
cation cylinder — in independent applications, directly by means of 
the independent brake valve; in automatic applications, by means 
of the equalizing portion and the air pressure stored in the pressure 
chamber. 

The well-known principle embodied in the quick-action triple 
valve, by which it gives a high braking power in emergency appli- 
cations and a sufficiently lower one in full-service applications to 
provide a desired protection against wheel sliding, is embodied in 
the ''No. 6" distributing valve. In describing the operation of the 
valve, reference will be made to the nine diagrammatic views shown 
in Figs. 97 to 106. For convenience, the chambers of the reservoir 
are indicated at the bottom as being a part of the valve. 

Automatic Brake Operation 

Charging. Referring to Fig. 97, which shows the parts in the 
release position, it will be seen that as chamber p is connected to the 
brake pipe, brake-pipe air flows through the feed groove v over the 
top of piston 26 into the chamber above equalizing valve 31, and 
through port o to the pressure chamber, until the pressures on both 
sides of the piston are equal. 

Service. When the engineer wishes to make a service applica- 
tion by the use of the automatic brake valve, the brake-pipe pressure 
in chamber p is reduced, the amount of this reduction depending 
on the degree with which it is desired to set the brakes. This action 
causes a difference in pressure on the two sides of piston 26, which 
causes the piston to move toward the right until it occupies the 
position shown in Fig. 98. The first movement of piston 26 closes 
the feed groove v, and at the same time moves the graduating valve 
28 until it uncovers the upper end of the port z in the equalizing 
valve 31. As piston 26 continues its movement toward the right, 
the shoulder on the end of its stem comes in contact with the left 
end of equalizing valve 31, which is then also moved to the right 
until the projecting piece on the right of the piston strikes the equal- 
izing piston graduating sleeve 44- The initial tension of the gradu- 
ating spring 46 prevents further movement of the piston and attached 
parts, unless an emergency application has been made, as explained 



AIR BRAKES 



121 



later, instead of a service application. With the parts in this posi- 
tion, port z in the equaHzing valve registers with port h in its seat, and 
cavity n in the equalizing valve connects ports h and lo in the seat. 
As the equalizing valve chamber is always in communication with the 
pressure chamber, and with the parts in the position illustrated in 



MR 




rig. 98. Automatic Service Position ol Dislnbuting Valve 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

Fig. 98, air can flow from the pressure chamber to both the appli- 
cation cylinder and the application chamber. This air pressure 
from the pressure chamber acting on piston 10 moves it to the right, 
as shown, causing exhaust valve IG to close exhaust ports e and d, 
and acts with sufficient force to compress application piston gradu- 
ating spring 20. As piston 10 is moved to the right, it carries with 



122 



AIR BRAKES 



it application valve 5, by means of its connection with the piston 
stem through the pin 18. With the appHcation valve in the posi- 
tion shown, its only port is fully opened and air is permitted to flow 
from the main reservoirs into chambers bb and through passage c 
to the brake cylinders. Air from the main reservoirs will continue 



MR 




Fig. 99. Service-Lap Position for Distributing Valve 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

to flow, through the path indicated above, into the brake cylinders 
until full equalization occurs. 

During the movement just described, cavity t in the graduating 
valve 28 connects ports r and s in the equalizing valve, and by the 
same movement ports r and s are brought to register with ports h and / 
in the seat. This establishes communication between the application 



AIR BRAKES 12:^ 

cylinder and the safety valve, wliich, being set at C8 pounds (three 
pounds above the maximum obtained in an emergency application 
from 70 pounds brake-pipe pressure), limits the brake-cylinder 
pressure to this amount. 

The amount of pressure resulting in the application cylinder 
for a certain brake-pipe service reduction depends on the compara- 
tive volumes of the pressure chamber, application cylinder, and its 
chamber. These volumes are such that with 70 pounds in the 
pressure chamber they will equalize at about 50 pounds. 

Service Lap. When the brake-pipe reduction is not sufficient 
to cause a full-service application, the conditions described above 
continue until the pressure in the pressure chamber is reduced 
enough below that in the brake pipe to cause piston 26 to force 
graduating valve 28 to the left until stopped by the shoulder on the 
piston stem striking the right-hand end of equalizing valve Sly the 
position indicated in Fig. 99 and known as service lap. In this 
position, graduating valve 28 has closed port z so that no more air 
can flow from the pressure chamber to the application cylinder and 
chamber. It also has closed port s, cutting off communication to 
the safety valve, so that any possible leak in the latter cannot reduce 
the application-cylinder pressure, and thus similarly affect the pres- 
sure in the brake cylinders. The flow of air past application valve 
5 to the brake cylinders continues until their pressure slightly exceeds 
that in the application cylinder, when the higher pressure and appli- 
cation-piston graduating spring together force piston 10 to the left, 
Fig. 99, thereby closing port h. Further movement is prevented 
by the resistance of exhaust valve 16 and the application-piston 
graduating spring having expanded to normal position. 

From the above description it will be seen that application 
piston 10 has application-cylinder pressure on one side g and brake- 
cylinder pressure on the other. When either pressure varies, the 
piston will move toward the lower. Consequently, if pressure in 
chamber h is reduced by brake-cylinder leakage, the pressure main- 
tained in the api)lication cylinder g will force piston 10 to the right, 
opening application vah'e 5 and again admitting air from the main 
reservoirs to the brake cylinders until the pressure in chamber h is 
again slightly above that in the application cylinder g, when the 
piston again moves back to lap position. 



124 AIR BRAKES 

Automatic Release. When the automatic brake-valve handle 
is placed in release position, and the brake-pipe pressure in chamber 
p is thereby increased above that in the pressure chamber, equalizing 
piston 26 moves to the left, carrying with it equalizing valve 31 
and graduating valve 28 to the position shown in Fig. 97. The 
feed groove v now being open permits the pressure in the pressure 
chamber to feed up until it is equal to that in the brake pipe, as before 
described. This action does not release the locomotive brakes 
because it does not discharge application-cylinder pressure. The 
release pipe is closed by the rotary valve of the automatic brake 
valve, and the application-cylinder pipe is closed by the rotary 
valves of both brake valves. To release the locomotive brakes, the 
automatic brake valve must be moved to running position. The 
release pipe is then connected by the rotary valve to the atmosphere 
and, as exhaust cavity k in the equalizing valve 31 connects ports 
i, tc, and h in the valve seat, the air in the application cylinder and 
chamber will escape. As this pressure reduces, the brake-cylinder 
pressure will force application piston 10 to the left until exhaust 
valve 16 uncovers exhaust ports d and e, allowing brake-cylinder 
pressure to escape. Fig. 97, or in case of graduated release, to reduce 
in like amount to the reduction in the application-cylinder pressure. 

Emergency. When a sudden and heavy brake-pipe reduction 
is made, as in an emergency application, the air pressure in the 
pressure chamber forces equalization piston 26, Fig. 100, to the 
right with sufficient force to compress equalizing-piston graduating 
spring 4^, and to seat against the leather gasket beneath cap 23. 
This movement causes equalizing valve 31 to uncover port h in the 
seat without opening port iv, making a direct opening from the 
pressure chamber to the application cylinder only, so that they 
quickly become equalized. This cylinder volume, being small and 
connected with that of the pressure chamber at 70 pounds pressure, 
equalizes at about 65 pounds. Also, in this position of the auto- 
matic brake valve, a small port in the rotary valve allows air from 
the main reservoirs to feed into the application-cylinder pipe, and 
thus to the application cylinder. The application cylinder is 
now connected to the safety valve through port h in the seat, cavity 
q and port r in the equalizing valve, and port I in the seat. Cavity 
q and port r in the equalizing valve are connected by a small port, 



AIR BRAKES 



12" 



the size of which permits the air in the apphcatioii cyhnder to escape 
through the safety valve at the same rate that the air from the 
main reservoirs, feeding through the rotary valve of the automatic 
brake valve, can supply it, preventing the pressure from rising above 
the adjustment of the safety valve. 



MR 




i ifi. loo. i>iin ij^i .11 .N 1 w.-iuon for Distributing Valve 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 



In high-speed brake service, the feed valve is regulated for 110 
pounds l)rakc-])ipe pressure instead of 70, and main-reservoir pres- 
sure is 130 or 140 pounds. Under these conditions an emergency 
application raises the application-cylinder pressure to about 93 
pounds; but the passage between cavity q and port r is so small that 



126 



AIR BRAKES 



the flow of application-cylinder pressure to the safety valve is just 
enough greater than the supply through the brake valve to decrease 
that pressure in practically the same time and manner as is done by 
the high-speed reducing valve, until it is approximately 75 pounds. 
The reason why the pressure in the application cylinder, pressure 



MR 




Fig. 101. Emergency Lap Position for Distributing Valve 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

chamber, and brake cylinders does not fall to 68 pounds, to which 
pressure the safety-valve is adjusted, is because the inflow of air 
through the brake valve with the high main-reservoir pressure used 
in high-speed service is equal, at 75 pounds, to the outflow through 
the small opening to the safety valve. This is done to get a shorter 
stop in emergency. The apphcation portion of the distributing 



AIR BRAKES 127 

valve operates similarly, but more quickly than in service application. 

Emergency Lap. The movable parts of the valve remain in 
the position shown in Fig. 100 until the brake-cylinder pressure 
slightly exceeds the application-cylinder pressure, when the appli- 
cation piston and application valve move back to the position 
known as ^'emergency lap" as shown in Fig. 101. 

The release after an emergency is brought about by the same 
manipulation of the automatic brake valve as that following service 
application, but tlie effect on the distributing valve is somewhat 
different. When the equalizing piston, equalizing valve, and gradu- 
ating valve are forced to the release position by the increased brake- 
pipe pressure in chamber j), the application chamber — pressure in 
which -is zero— is connected to the application cylinder, having 
emergency pressure therein through port w, cavity k, and port h. 
The pressure in the application cylinder at once expands into the 
application chamber until these pressures are equal, which results 
in the release of brake-cylinder pressure until it is slightly less than 
that in the application cylinder and chamber. Consequently, in 
releasing after an emergency (using the release position of the auto- 
matic brake valve), the brake-cylinder pressure will automatically 
reduce to about 15 pounds, where it will remain until the auto- 
matic brake-valve handle is moved to running position. 

If the brakes are applied by a conductor's valve, a burst hose, 
or parting of train, the movement of equalizing valve 31 breaks the 
connection between ports h and i through cavity k, so that the brakes 
will apply and remain applied until the brake-pipe pressure is 
restored. The handle of the automatic brake valve should be imme- 
diately moved to emergency position to prevent a loss of main- 
reservoir pressure. 

Independent Brake Operation 

Independent Application. When the handle of the independent 
brake valve is moved to either slow- or quick-application position, 
air from the main reservoir, limited by the reducing valve to a maxi- 
mum of 45 pounds, is allowed to flow to the application cylinder, 
forcing application piston 10 to the right as shown in Fig. 102. 
This movement causes application valve 5 to open its port and 
allow air from the main reservoirs to flow into chambers bb and 
through passage c to the brake cylinders, as in an automatic apph- 



128 



AIR BRAKES 



cation, until the pressure slightly exceeds that in the application 
cylinder. The application-piston graduating spring 20 and higher 
pressure then force application piston 10 to the left until appUcation 
valve 5 closes its port. Further movement is prevented by the 
resistance of exhaust valve 16 and the appUcation-piston graduating 



«S 




Fig. 102. Independent Application Position for Distributing Valve 
Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

spring having expanded to its normal position. This position, shown 
in Fig. 103, is known as "independent lap". 

Independent Release. When the handle of the independent 
brake valve is moved to release position, a direct opening is made 
from the application cylinder to the atmosphere. As the applica- 
tion-cylinder pressure escapes, brake-cylinder pressure in chamber b 



AIR BRAKES 



129 



moves application piston 10 to the left, causing exhaust valve 16 to 
open exhaust ports c and d as shown in Fig. 97, thereby allowing 
brake-cylinder pressure to discharge to the atmosphere. 

If the independent brake valve is returned to lap before all the 
application-cylinder pressure has escaped, the application piston 10 



MR 




Fig. 103. Independent Lap Position for Di.stributing Valve 
Courtesy of Wcstinyhouse Air Brake Company, Wilmerding, Pennsylvania 



will return to independent lap position, Fig. 103, as soon as the 
brake-cylinder pressure is reduced a little below that remaining in 
the appUcation cylinder, thus closing exhaust ports e and d and 
holding the remaining pressure in the brake cylinders. In this way 
the independent release may be graduated as desired. 



130 



AIR BRAKES 



Fig. 104 shows the position the distributing valve parts will 
assume if the locomotive brakes are released by the independent 
brake valve after an automatic application has been made. This 
results in the application portion going to release position without 
changing the conditions in either the pressure chamber or brake 




Fig. 104. Release Position for Distributing Valve 
Courtesy of Westinghouse Air-Brake Company, Wilmerding, Pennsylvania 



pipe; consequently, the equalizing portion does not move until 
release is made by the automatic brake valve. 

An independent release of locomotive brakes may also be made 
in the same manner, after an emergency application by the auto- 
matic brake valve. However, owing to the fact that, in this posi- 



AIR BRAKES 



131 



tlon, the automatic brake valve will be supplying the application 
cylinder through the maintaining port in the rotary valve, the 
handle of the independent brake valve must be held in release posi- 
tion to prevent the locomotive brakes from re-applying so long as 
the handle of the automatic brake valve remains in emergency 
position. The equalizing portion of the distributing valve will 
remain in the position shown in Figs. 100 and 101. 

Double=Heading. When 
there are two or more locomo- 
tives in a train, the instruc- 
tions already given remain 
unchanged so far as the lead- 
ing locomotive, or the locomo- 
tive from which the brakes are 
being operated, is concerned. 
On all other locomotives in the 
train, however, the double- 
heading cock under the auto- 
matic brake valve must be 
closed and the automatic and 
independent brake-valve han- 
dles carried in running posi- 
tion. The release pipe is then 
open to the atmosphere at the 
automatic brake valve, and 
the operation of the distribut- 
ing valve is the same as that 
described during automatic 
brake applications. In double 
heading, therefore, the appli- 
cation and the release of the distributing valve on each helper loco- 
motive is similar to that of the triple valves on the train. Port u 
drains the application cylinder of any moisture precipitated from 
the air in chamber h, such moisture passing to the lower part of the 
distributing valve through port ?», where it may be drawn off by 
removing the pipe plug. 

Quick=Action Cylinder Cap. The equalizing portion of the dis- 
tributing valve corresponds to the plain triple valve of the old 




Fig. 105. Section Showing Quick-Action Cylinder 
Cap for No. G Distributiiig Valve 
Courtesy of Westinghouse Air Brake CompaJiy, 
Wilmerding, Pennsylvania 



132 



AIR BRAKES 



standard locomotive brake equipments. There are, however, con- 
ditions under which it is advisable to have it correspond to a quick- 
action triple valve; that is, vent brake-pipe air into the brake cyl- 
inders in an emergency application. To obtain this, the cylinder cap 
23, Fig. 96, is replaced by the quick-action cylinder cap, Fig. 105. 
In an emergency application, as equalizing piston 26 moves to 
the right and seals against the gasket, Fig. 106, the knob on the 




Fig. 106. Emergency Position of No. 6 Distributing Valve with Quick-Action Cap 

Courtesy of Westinghouse Air Brake Company, Wilmerding, Pennsylvania 

piston strikes the graduating stem 50, causing it to compress equal- 
izing-piston graduating spring 55, and move emergency valve 48 
to the right, opening port j. Brake-pipe pressure in chamber p 
flows to chamber X, pushes down check valve 53, and passes to 
the brake cylinders through port m in the cap and distributing 
valve body. When the brake cylinders and brake pipe equalize, 



AIR BRAKES 133 

check valve 53 is forced to its seat by spring 54, thus preventing air 
in the brake cyUnders from flowing back into the brake pipe. When 
a release of the brakes occurs and piston 26 is moved back to its 
normal position, Fig. 97, spring 55 forces graduating stem 50 and 
emergency valve 4^ back to the position shown in Fig. 105. 

"PC" PASSENGER BRAKE EQUIPMENT 

Characteristics. The 'TC passenger brake equipment was 
designed for fast passenger service and for cars weighing as high 
as 150,000 pounds. Briefly stated, the requirements recognized as 
essential in a satisfactory brake for this modern service are as follows: 

(a) Automatic in action. 

(b) Efficiency not materially affected by unequal piston travel or brake-cylinder 
leakage. 

(c) Certainty and uniformity of service action. 

(d) Graduated release. 

(e) Quick re-charge and consequent ready response of brakes to any brake-pipe 
reduction made at any time. 

(f) Maximum possible rate of re-charging the brake pipe alone. 

(g) Predetermined and fixed flexibility of service operation. 

(h) Maximum sensitiveness to release, consistent with stability, combined with 
minimum sensitiveness to the inevitable fluctuations in brake-pipe pressure 
tending to cause undesired light-service applications, brakes creeping on, etc., 
and yet guard against the attainment of too high a difference of pressure 
between the brake pipe and the pressure chamber (auxiliary reservoir). 

(i) Full emergency pressure obtainable at any time after a service application. 

(j) Full emergency pressure applied automatically after any predetermined 
brake-pipe reduction has been made after equalization. 

(k) Emergency braking power approximately 100 per cent greater than the 
maximum obtainable in service applications. 

(1) Maximum brake-cylinder pressure obtained in the least possible time. 

(m) Maximum brake-cylinder pressure maintained throughout the stop. 

(n) Brake rigging designed for maximum efficiency. 

(0) Adaptability to all classes and conditions of service. 

Special Features of "PC" Equipment. The construction and 
principle of operation of the *'PC" brake equipment is such as to 
permit of the fulfillment of all of the above requirements. The 
features which may be mentioned as being peculiar to the equipment 
are as follows: 

(1) Graduated release and quick re-charge obtained as with previous improved 
types of triple valves. 

(2) Certainty and uniformity of service action. 

(3) Quick rise in brake-cylinder pressure. 



134 AIR BRAKES 

(4) Uniformity and maintenance of service brake-cylinder pressure during the 
stop. 

(5) Predetermined limiting of service braldng power. 

(6) Automatic emergency application on depletion of brake-pipe pressure. 

(7) Full emergency braking power at any time. 

(8) The service and emergency features being separated permits the necessary 
flexibility for service applications to be obtained without impairing in the 
slightest the emergency features of the equipment. 

(9) A low total leverage ratio, with corresponding over-all efficiency. 

(10) Less sensitiveness to the inevitable fluctuations in brake-pipe pressure, 
which tend to cause undesired light applications of the brake. 

(11) Maximum rate of rise of brake-pipe pressure possible with given length 
of brake pipe, with consequently greater certainty of brakes releasing when a 
release is made. 

(12) Greatly increased sensitiveness to release in long trains, when it becomes 
necessary to have the maximum sensitiveness to an increase in brake-pipe 
pressure to insure all valves in the train responding as intended. 

(13) The elimination of the graduated release feature is specially provided for 
in the construction of the valve. This is provided for to permit the use of 
cars not equipped with a graduated release brake. 

All of the functions mentioned above have been combined in 
such a way that they will interchange with existing equipments in 
an entirely satisfactory manner. 

Names of Various Parts and Their Identification. Fig. 107 
shows all of the parts making up the equipment, together with their 
names. It also illustrates the two methods of installation. The 
following is a list of the names of the various parts, a number of 
which have previously been described in connection with other 
brake equipments: 

(1) The "No. 3-E" control valve, corresponding in a general way to the triple 
valve of the old-style passenger equipment, and more closely to the distributing 
valve of the "ET" equipment. 

(2) Two brake cylinders — one for service and both for emergency applications. 

(3) Two supply reservoirs, called the service and emergency reservoirs, 
respectively. 

(4) A centrifugal dirt collector. 

(5) A branch-pipe air strainer. 

(6) A conductor's valve. 

(7) A branch-pipe tee, cut-out cocks, angle cocks, hose couplings, dummy 
couplings, etc., similar to those found on other equipments. 

(8) An automatic slack-adjuster, which is not an essential part of the equip- 
ment, but which is strongly recommended. 

Of all the parts making up the equipment, the control valve illus- 
trated in Figs. 108, 109, and 110, is the most important. As can be 
seen, the valve portions are supported upon the compartment reser- 



AIR BRAKES 



135 




136 AIR BRAKES 

voir, which is bolted to the underframing of the car. The compart- 
ment reservoir is made up of the pressure chamber, apphcation 
chamber, and the reduction-hmiting chamber. The equaUzing and 




Fig. 108. Westinghouse "3-E" Control Valve, Showing Side View 

apphcation portions of the compartment reservoir correspond to 
those of the "ET" equipment. The location and size of the pipe con- 
nections are more clearly shown in the outline drawings. Figs. Ill 
and 112. Actual sections of the control valve and compartment 
reservoir are shown in Figs. 113, ^^^m^ ^M^^ 

114, and 115, having all of the parts e^pM^^H^^^BP^4^^H|B| 
numbered. The following five par- g^^^B^^^Br^J^S^^^^l 
agraphs are arranged to assist in Wt ' - ^HI^^^S^B^B 
identifying the various parts: m^ - ^^F 

Equalizing Portion: 2 Equalizing ^^^^Hk^t? ^^Vi 

body; 3 Release piston; 4 Release slide ^^^^Hl^^ ' | 

valve; 5 Release slide-valve spring; 6 Re- ^^^^^^^K^ J 

lease graduating valve; 7 Release gradu- ^^^^^^^^K 

ating-valve spring; 8 Release piston-cap ^^^^^^^^B 

nut; 9 Release piston ring; 10 Release cyl- ^^^^^^^^K| 

inder cap; 11 Release cylinder-cap gasket; ^HI^^^^^B 

12 Square-head cap screw; 13 Release pis- BI^^^^^^^h 

ton graduating sleeve; 14 Release piston ^^^^^^^^^B'^I^^^^B. 

graduating spring; 15 Release piston grad- ^^^^^^^^^^ T^^^^- — 

uating nut; 16 Check valve; 17 Check- ^. ^ , 

vnlvp Pin nut- 1R Dirppf nnH o-rnrlnnfprl ^^^- 109. Westinghouse "3-E Control 

vaive cap nui, i^^ V^^®^5 . graauatea ^^^ Showing Front View 

release cap; 19 fetud and nut for direct 

and graduated release cap; 20 Equalizing piston; 21 Equalizing piston ring 
(large) ; 22 Equalizing slide valve; 23 Equalizing slide-valve spring; 24 Equalizing 
graduating valve; 25 Equalizing graduating-valve spring; 26 Large equalizing 
cylinder cap ; 27 Large equalizing cylinder-cap gasket ; 28 Square-head cap screw ; 
29 Equalizing piston-stop sleeve; 30 Equalizing piston-stop spring; 31 Equali- 
zing graduating nut; 32 Equalizing piston ring (small); 33 Small equalizing cyl- 
inder cap; 34 Gasket for small equalizing cylinder cap; 35 Square-head cap 
screw; 36 Cap nut for small equalizing cy Under cap; 37 Small equalizing pis- 



AIR BRAKES 



137 




Fig. 110. Westinghousc "3-E" Control Valve, Showing Dififerent 
Portions of Valve 



■ 5 






-/o'4 



A:^ 



rZr\ 




j- r f 1 . I rr T 



Drill- 
f Pipe Sen Cijl E>i 
I "Pipe Sen Hep 

/ "Brake PipejQ 
./7ppl. Chamber'L'.AhO'jsi 



I "Pipe Quick 
ffclion Ex. 
■ /Sg 




fPipe ^ 
Peduclwn 
Limiting 
Cl^amberEx 




Fig. 111. Outline of Westinghouse "3-E" Control Valve 



A^^ 



LTD 




^^ §Pipe 

£mer^ency Piston Exh. 



"/ Pipe -Seri/ice Cylinder 
(^^r-Dram 

(T^Tf^ Pips Emergency Re s. 

\C^/J^ Pips Emergency Cylinder 




©HQIZipOnQi Emerge nc^ Cylinder Exh 



Fig. 112. Outline of Westinghouse "3-E" Control Valve, Showing 
Side Opposite to That of Fig. Ill 



138 



AIR BRAKES 




137-^ 



Fig. 113. Actual Longitudinal Section of Westinghouse "3-E" Control Valve 






15' 



Hpplicofiori Chamber 



Y^i"-^ii- 




Pipe 
ServLce 
Tfeservoir 

'Pipe 
Service 
"Reservoir 

"Pipe 
fJppHcalion 
'Chambei' 
Exhaust 



I "Pipe 
Emergenci^ 
Heseryoir 

I09 
I ''Pipe 
Emergency 
Culmder 



"Pipe 
"Brake Pipe, 
1^3 



JI3 "8 



J08 



/ri 



136 



/30 



Fig. 114. Actual Cross Section of Westinghouse "3-E" Control Valv« 



AIR BRAKES 



139 




ton bush; SS Service-rosorvoir charging valve; 39 Charging-valve piston 
ring; 40 Charging-valvo piston ring; 41 Charging-valve seat; 4^ Charging-valve 
washer; 43 Internal charging-valve nut; 44 External charging-valve nut; 4^ 
Gasket for direct and graduated release cap. 

Application Portion: 75 Body; 76 
Piston stem; 77 Piston ring (small); 78 
Piston head; 79 Piston seal; .^r; Piston 
ring (large); 81 Piston follower; 82 Pis- 
ton-packing leather; 83 Piston-packing 
leather expander; 84 Piston nut; 85 Pis- 
t on cott er ; 86 Exhaust valve ; 87 Exhaust- 
valve spring; 88 Application valve; 89 
Application-valve spring ; 90 Applicat ion- 
piston bolt; 91 Spring box; 92 Piston- 
spring sleeve; 93 Piston spring; 94 Grad- 
uating nut; 95 Application-valve cover; 
96 Application-valve cover gasket; 97 
S(iuare-head screw for application-valve 
cover. 

Emergency Portion: 107 Body ; 108 
Piston complete! 109 Piston ring; 110 
Slide valve; 111 Slide-valve spring; 112 
Small cyhnder cap; 113 Large cylinder 
cap; 114 Small cylinder-cap gasket; 115 
Large cylinder cap gasket; 116 Piston 
spring; 117 Square-head cap screw for 
small cylinder cap; 118 Oval fillister head 
cap screw; 119 Emergency-piston bush. 

Quick-Action Portion: 130 Body; 

131 Piston complete; 132 Piston ring; 

133 Quick-action valve ; 134 Quick-action 
valve seat; 135 Quick-action valve nut; 136 Quick-action valve spring; 137 
Quick-action valve cap nut; 138 Quick-action valve cover; 139 Quick-action 
closing valve; i^O Quick-action closing valve spring; I4I Cover cap nut; 142 
Cover gasket; 143 Square-head cap screw for cover. 

Reservoir: 153 Triple-compartment reservoir; 154 Cap nut; 155 Stud 
with hex. nut; 156 Stud with hex. nut; 157 Emergency-cylinder gasket; 158 
Quick-action cylinder gasket; 159 Large reservoir gasket; 160 Equahzing-cylinder 
gasket. 

CONTROL VALVE 

Fig. 116 is presented to assist in gaining a clearer idea of the 
location of the parts in the different portions of the control valve. 
On account of the comphcated construction of the ''No. 3-E" control 
valve, reference will be made to the diagrammatic views shown in 
Figs. 117 to 131, in explaining its action. 

Fig. 117 shows all of the ports and operative parts of the control 
valve in normal position. This is the position which the various 
parts of the valve would occupy with all parts properly assembled, 
but before any air has been admitted to the brake pipe. 

It will be noted that the direct- and graduated-release cap is 
shown in its graduated-release position. Just below it is shown the 
position which the cap occupies when adjusted for direct instead of 



Fig. llo. Section through EquaUzinj 

Portion of Wcstinghousc "3-E" 

Control Valve 



140 



AIR BRAKES 



graduated release. In all the succeeding views, except Fig. 129, 
the cap is considered to be adjusted for graduated release. Fig. 




■.^^/ 






Piston Brake-Pipe 



Broke Pipe 



'WTll 

A Service Cylinder Exhaust. 

B Service Reservoir. 

C Upper Side of Equalizing 

Pressure. 
D Application-Chamber Exhaust. 
E Not Used. 

F Lower Side of Quick-Action Closing Valve 
H Reduction-Limiting Chamber. 
/ Large Emergency Piston. 
J Emergency Reservoir. 
K Back Side of Application Piston. 
L Small Emergency Piston. 
M Application Chamber. 
A'^ Service-Brake Cylinder. 
O Pressure Chamber. 
X Emergency-Cylinder Exhaust. 
Y Port Connecting Emergency Brake Cylinder with 

Quick-Action Valve. 
Z Port Leading from Service-Brake Cylinder to 

Emergency Valve. 

All Holes Not Designated Are Bolt Holes. 

Fig. 116. Diagrams of Flanges and Seats for Westinghouse "3-E" 
Control- Valve Portions 




Emer.Ci^l 



£QuoUzfnQ Grvd Sprinq TfelSaseGrad- Spring fressure Chamber Check VaJve 

7 V _L_'^ y /r-„. .„/._.„., _J^ Release 

Choml^x. fSer. Cul. Ex. rSer I?es. 



£quolizing 

Piston 
Emerg. Ifes. 
Check \tflve 

Sen Res. 
Charging 

Valve 

Equalizing_ 
Grad. Valve 

ffeduciion 

Limiting _^ 
Chamber 

Exhaust 

Equahdng 
Slide Valve 

Release 

Qrad- Valve 
K 
Egualiring 
PislonSiop 




Eejuahzinq Slop Spring Em erg. Piston 

Position forCradReJ. 
Hired & Grad. Re I. Cap 
Position for Di reel Rel 



Quick fiction 



'/ ^£merCc/l.\ Quick fJclion Ek. Valve 
^„ r.,1 e.. Emerq.Res. \ 



Emerg Cl/LEx. E^ner^ 



Em en Slide Valve 



Fig. 117. Normal Position of Westinghouse "3-E" Control Valve 

129 with the accompanying explanation refers to the operation of 
the valve with the cap adjusted for direct release. 



AIR BRAKES 



141 



Release and Charging Position 

Fig. 118 shows only those parts and ports which are operative 
while the brake is being released and the pressure chamber and 
emergency and service reservoirs are being charged. 

Charging Empty Equipment. In charging the empty equip- 
ment, air from the brake pipe entering the control valve at the point 
indicated passes to chambers B and A and forces the equalizing and 
release pistons of the equalizing portion, with their attached valves, 
to release position. Brake-pipe air then passes from chamber B, 
lifting the equalizing check valve, and by way of the equalizing slide 



Spring. 



Release G^ad Spring 



Equalizing 
Fisfon ' 
EmerRes. 
Check Valve 

SenJfes. 
Charging Valve 

Equalizing 
Qnod. Valve ^ 

Reduction 

Li mil in q~ 

ChamberEx. 

Equalizing 
Slide Valve ' 



Equalizing- 
Piston Step 



er. Res. 




'^ ReleoseSiide Valve , ;. .^wf i rvx ■ 

Emergency Piston Ex Jdjj* 

equalizing Stop Spring nirecl&Grad RelCap ^ 

Position for Crad. Release Sen Cgl' 

Em'erg. Cyl. Ex. Emerg. Res- 

Fig. 118. Release Position, Charging-Pressure Chamber, Emergency and 
Service Reservoirs for Westinghou'se "3-E" Control Valve 



valve into chamber J). Air from chamber J) then flows through 
the equalizing graduating and slide valve — so shown in the dia- 
grammatic drawing for the sake of clearness. In this and a number 
of instances following, this port in actual valves opens past the end 
of instead of through the graduating valve, past the emergency- 
reservoir check valve, and thence in two directions: (1) to chamber 
R and to the emergency reservoir, and (2) through the equalizing 
slide valve to two different ports, one connecting to the service- 
reservoir charging valve and thence to the service reservoir; the. 
other by way of the direct- and graduated-release cap and through 



142 AIR BRAKES 

the release slide valve and past the end of the release graduating 
valve to eham})er E. 

Air from tlui brake pii)e and (•ham})er Ji also flows through 
feed groove i and charges chaniher K. From chamber E, the air 
flows by way of the eciualizing slide valve in two directions: (1) 
to the pressure chamber direct (which is thus charged to brake-pipe 
pressure), and (2) to chamber K. With substantially the same 
pressures (brake-i)ii)e i)ressure as exi)lainc(l) in chaml)ers (J and K, 
and a lower pressure (service-reservoir pressure) in (chamber //, the 
service-reservoir charging valve remains in the position shown in 
Fig. 117, being held in this i)osition until the re-charging is com- 
I)lete(l, since chamber K is relatively small and the ports leading 
to it of ample capacity to charge it more (juickly than the pressure 
can be built u\) in chnmbers (/ and //. 

Release Connections. ]{eferring to Fig. 117, it will be noted 
that the pressure-chamber check valve prevents the air in chamber 
E from flowing directly to the pressure chamber, but allows a free 
passage of air in the opposite direction. 

Chamber F at the small end of the equalizing piston is connected 
through the release slide valve to the emergency-pistcm exhaust and 
atmosi)here, thus holding the equalizing piston and its valves posi- 
tively in release position. Chamber S at the small end of the 
emergency piston is connected through the relc^asci slide valve to 
the em(Tgcncy-])iston exhaust and the atmosphere in release posi- 
tion, thus holding the emergency piston and its valve positively in 
the pr()i)er i)()siti()n. 

Tlve reduction-limiting chamber is connected througli the 
equalizing slide valve to the reduction-limiting chamber exhaust 
and atmosphere, 'i'he application chamber and chaml)er (' are 
connected through the release slide valve and graduating valve to 
the jjpplication-chamber exhaust port leading to the atmosphere. 

The service brake cylinder is cormected through the exhaust 
slide valve of the a])])lication ])()rtion to the service brake-cylinder 
exhaust i)()rt leading to the atm()si)lKTe. The emergency brake 
cylinder is connected through the emergency slide valve to the 
emergency-cylinder exhaust port leading to the atmosphere. 

It will be noted that Fig. 117 and some that follow show a small 
cavity in the release graduating valve. This cavity is connected to 



AIR BRAKES 



143 



the cmcr^cnoy-piston oxliaiist in all positions of the valve, but has 
no other connection. The ])nrp()se of this cavity is merely to insure 
that, under all conditions, there will he sufhcient dillerential pres- 
sure acting on the graduating valve to hold it to its seat. 

Service Application 

(a) Preliminary Service Position. With the equipment fully 
vharged as explained above, the result of a service reduction in brake- 
])il)e pressure will be to lower the pressure in chambers A and B 
below that in chambers./) and E, thus creating a differential pres- 



Equoli ling Orad. Spring Release G rod Pressure Chamber 

Spring ot— > Ffeleose Check Valve 



Equaliring- 
Pi'ston 
D 



Cqualiring 
Grad. Valve — 

Re dud I on 

L(rrnling 

Chamber L'k. 

Eoualtzinu— ■ 
Sitae Valve 

Release ^\; 
Orod. Valve 

equalising • 
PtsfonSlo/j^ 



Sen Cgl. En. 




Egualiiincj 2 lop 'Jprinn 



PirectuQrod Rei Cop 



\Brake Pipe 



. Jlide Valve 



Emerq. Ct^l. En. Emerg. Res. 

FIk. 1 I!). I'r< limitiHry R(;rvi(!() Pr)si(,i()M of W(!sliii(^li()n.s(! ";i-I']" T'onlrol Valvo 



sure on the equalizing and release pist(ms. Since chamber F is open 
to the atmosphere, Fig. 11<S, the release piston will move on a nnicii 
less dif^'erential than the equalizing piston. There is a small amount 
of h)st motion between release piston and release graduating valve, 
and somewhat more between release piston and release slide valve 
so that during the first movement of the release piston, the release 
slide valve still remains in its release i)osition, thus keej)ing chamber 
F open through the emergency-])iston exhaust ])()rt to the atmos- 
phere. '^I'he rclcjise piston, tlujrefore, is the first to move when a 
brake-pipe reduction is made and it carries with it the release gradu** 
ating valve and finally moves the release slide valve to the position 



144 



AIR BRAKES 



shown in Fig. 119, called preliminary service position. In this position 
the piston has closed the feed groove i (which is therefore not shown 
in Fig. 119) and just touches the release graduating-piston sleeve. 
The function of the valve in this position is to close the port 
leading from the application chamber to the atmosphere (which is 
therefore not shown in Fig. 119), to close the port connecting cham- 
ber F to the emergency-piston exhaust, and to open this latter port, 
connecting chamber E past the end of the release graduating valve 
and through the release slide valve to chamber F. Pressure-cham- 
ber air is, therefore, free to flow past the pressure-chamber check 



Equalizing^ 
Gradualing 
Spring 



ffeleose 

Piston 



Pressure Chamber 

Check Valve ^ . ^ ,. ^ ^ 
"Service Cylinder £x. 



Equalizing 
Fislcn 



Equalizing m ^^[^^^; 

Cradualing --^~ M$$^ 

Valve 
deduction 

LimilingChambe ^ . 

Felease 
Orad Valve 
Equalizing 
Slide 
Valve 



Equalizing^ 
Piston 3 top 



Equalizing 
Slop Spring 




Direct vQroduoled Release Cop 

Service 
Emergency Ci^linderEK. 



Cylinder^ 



^Emerg. Slide Valve 
^iEV77 ergencg Reservoir 



Emergency Cylinder 
Fig. 120. Secondary Service Position of Westinghouse "3-E" Control Valve 

valve to chamber F, thus balancing the pressures in chambers F and 
B on the opposite sides of the small end of the equalizing piston. 

This position, it should be understood, is assumed only momen- 
tarily and should be regarded as the first stage only of the complete 
movement of the parts from release and charging to the service 
position of the parts. 

(b) Secondary Service Position. The balancing of the pres- 
sures in chambers F and D, as explained, permits the equalizing 
piston to move in accordance T\dth the difference of pressure already 
existing between chambers D and A. When the shoulder on the 
end of the piston stem comes in contact with the equalizing slide 



AIR BRAKES 



145 



valve, as sho\\Ti in Fig. 120, a connection is momentarily made from 
the emergency reservoir through the equalizing slide valve and past 
the end of (although shown as through in the view) the graduating 
valve to chamber ]). The purpose of this connection is to prevent 
a drop in pressure in chamber D which would otherwise take place 
on account of the movement (disi)lacement) of the equalizing piston. 
The displacement of the equalizing piston is sufficiently great, com- 
pared with the volume of chamber 1), to require the provision just 
explained. 

At the same time, the pressure chamber is connected through 
the equalizing slide valve and graduating valve to chamber D, thus 



Equalizing Grad. 
Spring 



Release Gnad. 



Pressure Chamber 
Check Valve 



Sen Res. 




PislonJlop \|;F^^ ' ■ ■' 



EquQhtmgSlop Spring oirec^QradReLCap 

5er Cgl. -^ j Emenj. Cgi 

Emerg. Cgl- Ex.. "Cmerg. Res. 

Fig. 121. Service Position of Westinghouse "3-E" Control Valve 



Err>erg. Slide Valve 



keeping the pressures in these two chambers equal. The other 
connections remain as explained under the heading 'Treliminary 
Service Position '\ 

(c) Service Position. Tlic differential between the brake- 
pipe pressure in chamber A and the pressure in chamber J) (pressure- 
chamber pressure as explained) is sufficient to move the equalizing 
piston and its valves past the intermediate secondary service posi- 
tion into service position, Fig. 121, in which the equalizing piston 
just touches the equalizing graduating-spring sleeve. 

Chambers F and D are in communication by w^ay of a feed port 
around the small end of the equalizing piston. The pressure cham- 



146 



AIR BRAKES 



ber is connected to chamber D through two channels, first, by way 
of the pressure-chamber check valve to chamber E and thence past 
the end of the release graduating valve through the release slide 
valve to chamber D by w^ay of a port past the end of (showTi as 
through in diagram) the equalizing slide valve, as well as through 
chamber F ; and second, the pressure chamber is also connected 
directly to the seat of the equalizing slide valve and past the end of 
(shown as through in diagram) the slide valve direct to chamber B. 
From chamber D, air from the pressure chamber can flow past 
the end of the equalizing graduating valve and through the equalizing 



Equalizing Grad. 
Spring 



ffelease Grad. 
Sprir 



Release 



3en Res. 



Equalizing 
Pis ton - 



Equalizing 
Grad- Vah 



Reduction 

Limifing 
Charnber 

Sxhaust' 

Equalizingy^ 
Slide Valve 

Release 
Orad. Valve 
Equalizing 
Fislon Slop 



v//i / ^^'^'/yf(^'!ihr^// /^ 



'z flpp. Pi si on 
^ 3pring5leeyt 

Jfpp. Pislon 
VA Spring 

''/ _Reduction 
^ Limiling 





Equalizing SlcpSpring jpirect l^Gmd. Pel. Cap 



Sen Cyi- 

Emerg. Cgl Ex. 



Fig. 122. 



Emerg. 7?es. 
Service Lap Position for Westinghouse "3-E" Control Valve 



slide valve to the application chamber and chamber C on the face of 
the application piston. The pressure of the compressed air thus 
admitted to chamber C causes the application piston to move to its 
application position, compressing the application-piston spring in 
so doing. 

In this position the brake-cylinder exhaust slide valve closes the 
brake-cylinder exhaust ports (which, therefore, are not shown in Fig. 
121), and the application slide valve opens the application port, 
permitting air from the service reservoir (chamber N) to flow to 
chamber and the service brake cylinder, thus applying the brakes. 
The air flowing thus to the service brake cylinder also flows by way 



AIR BRAKES 



147 



of the emergency slide valve to chamber M, in which the pressure is 
increased equally with that of the ser\ice brake cylinder. The flow 
of air from the service reservoir to the service cylinder continues, 
therefore, until the pressure in the service brake cylinder and in 
chamber M becomes substantially equal to that in the a])])lication 
chamber on the opposite side of the application piston. The appli- 
cation-piston spring then returns the piston and the application 
slide valve back to lap position, Fig. 122, thus holding the brakes 
applied with a service brake-cylinder pressure substantially equal to 
that put into the application chamber, as before mentioned. 

It will be noted that in service position, the reduction limiting 
chamber and emergency brake cylinder still remain connected to 
the atmosphere, as explained under the heading "Release Position". 

(d) Service Lap Position. In case that less than a full-service 
reduction is made, that is to say that the brake-pipe pressure is not 



Equalizing Grad 



Release Grod. Pressure Chanb^ 

Sprinq^^TTs^ Release Cl^eck Valve SerRes 

wJll Piston I 

TZZZZZZiT^ZZ^ZZZ:?. 




Equalizing 
PisloiT 

Sen Res. 
Charging Valvi 

Equalizina 
Grad. Valve 

Reduction 
Limiting 
Chamber 
£'j(hausl 

Equalizing ; 

3lide Valve 

Release 
Grad Valve 

Equalizing 
Piston Stop 



Equalizina Slop Spring,- 



Ser Cgl 



Brake F^pe 

Em erg. Slide Valve 
Emerg Res. 



Em erg Cyl 
Emerg Col Ex 

Fig. 123. Over-Reduction Position for Westinghouse "3-E" Control Valve 



reduced below the point at which the pressure-chamber and appli- 
cation-chamber pressures equalize, the flow of air from the pressure 
chamber to the application chamber as explained under the heading 
^'Service Position" will finally reduce the pressure in chamber D to 
slightly below that to which the brake-i)ipe pressure is reduced. 
The slightly higher brake-pipe pressure in chamber A then causes 



148 AIR BRAKES 

the equalizing piston and graduating valve to return to their service 
lap positions, Fig. 122, and close communication from the pressure 
to the application chamber, holding whatever pressure was built 
up in chamber C and the application chamber. 

It will be plain that any decrease in brake-cylinder pressure, 
due to leakage, will now reduce the pressure in chamber M below 
that which is bottled up in the application chamber (chamber C). 
The differential pressure thus established on the application piston 
will cause it to move again toward its service position and open the 
application valve port, as shown in Fig. 123, just enough to supply 
a sufficient amount of air from the service reservoir to the service 
brake cylinder to restore the depleted brake-cylinder pressure to 
its original amount, following which the application valve will be 
again lapped as already explained. In this way, the brake-cylinder 
pressure will be maintained constant, regardless of leakage, up to 
the capacity of the service reservoir. 

The release piston and graduating valve may or may not return 
to their lap positions at the same time as, and in a manner similar 
to the movement of, the application piston and valves, but they 
perform no function in either case. Otherwise the parts remain 
the same as in service position. 

(e) Over=Reduction Position. If the brake-pipe reduction is 
carried below the point at which the pressure and application cham- 
bers equalize — 86 pounds w^hen using 110 pounds brake-pipe pres- 
sure and 54 pounds with 70 pounds brake-pipe pressure — such an 
over-reduction results in lowering the pressure in chamber A below 
that in chamber D (pressure-chamber pressure). The equalizing 
piston consequently moves beyond its service position, Fig. 121, 
carrying with it the equalizing slide valve and graduating valve to 
what is called the over-reduction position. 

The relative resistances of the release and equalizing graduating 
springs is such that the release piston and its valves still remain as 
in service, although for the moment the same differential between 
pressure-chamber and brake-pipe pressure is acting upon the release 
piston as was sufficient to move the equalizing piston and its valves 
to the over-reduction position. 

The result is that air from the pressure chamber — which is still 
connected to chamber D in substantially the same manner as 



AIR BRAKES 149 

explained under "Service Position" — now flows past the end of 
the equaHzin^ o:ra(hiating valve and throno^h the equalizing slide 
valve to the reduction-limiting chamber instead of to the applica- 
tion chamber as in service position. 

The reduction-limiting chamber being at atmospheric pressure 
permits the pressure in the pressure chamber (and chambers E and 
D) to drop, in accordance with the continued over-reduction of brake- 
pipe pressure, to the point of equalization of the reduced pressure- 
chamber pressure and the reduction-limiting chamber pressure. 
Othermse the condition of the pressures in the reservoirs and brake 
cylinders controlled by the control valve is unchanged, except that 
in the movement of the equalizing slide valve to over-reduction posi- 
tion, Fig. 123, a connection is made from the application chamber 
and chamber C by way of the equalizing slide valve to the top 
(chamber G) of the service-reservoir charging valve, and from 
chamber D (pressure-chamber pressure) past the end of the 
equalizing graduating valve and through the equalizing slide valve to 
chamber K. Since the pressure in the pressure chamber is being 
reduced, while that in the application chamber and service reservoir 
is equalized, or practically so, at about 86 pounds pressure, the ser- 
vice-reservoir charging valve is not lifted, but is held down to its seat. 

With the parts in this position, it will be noted that the service 
reservoir and the application chamber are separated only by the 
ring in the small end of the service-reservoir charging valve. If 
there is any slight leakage which tends to cause a drop in applica- 
tion-chamber pressure — which is relatively small compared with 
the service-reservoir volume — the air in the service reservoir will 
gradually find its way around the ring in the small end of the service- 
reservoir charging valve and prevent any material drop in applica- 
tion-chamber pressure, thus practically eliminating the possibility 
of the brakes gradually leaking off, due to application-chamber 
leakage. The application valve port is shown partly open, supply- 
ing brake-cylinder leakage, as already explained. 

(f) Over=Reduction Lap Position. Provided the brake-pipe 
reduction is not carried below the equalizing point of the pressure 
chamber and reduction-limiting chamber, a slight reduction of the 
pressure in the pressure chamber (and chambers D and E) below that 
held in the brake pipe, resulting from the continued flow of air from 



150 



AIR BRAKES 



the pressure chamber to the reduction-Hmithig chamber, will cause 
the equalizing piston and graduating valve to be returned to over- 
reduction lap position, Fig. 124. This closes the port from the pressure 
chamber to the reduction-limiting chamber and prevents further 
flow of air in this direction, but otherwise all parts and pressures are 
as explained under ''Over-Reduction Position", except that the port 
connecting chamber D past the end of the equalizing graduating 
valve and through slide valve to chamber K is blanked by the move- 
ment of the equalizing graduating valve. 

Should the brakes be held applied in over-reduction lap position 
for a sufficient length of time, with an application-chamber leakage 



Egualiring Grad 



Equalirinq 

Fislon 
5erRes. 
Charging Valve 
D 

Equalizing^ 
Grad. Valve 

Neduclion 
Limiting 
Chamber I 
Equalizinq 

5lide Vat 

Release 
Grad. Valve 
K 

Equalizing 
fislon Slop 



Release^rad 
Spring 




Equalizing Slop Spring 



Release 5li de Valve ^^ j: ^^ 

7 '-Li-' 

Dinedb'Gradlfel Cap 



Emer.Cgl. 
Emerg.CgiEx. 



Emerq. Slide Valve 
Emerg.Res 



Fig. 124. Over-Reduction Lap Position for Westinghouse "3-E" Control Valve 



so great that the air from the service reservoir could not get past the 
ring in the small end of the service-reservoir charging valve fast 
enough to supply such leakage (in the manner explained in connection 
with Fig. 123), the service-reservoir charging valve will finally be 
lifted, making wide open connection from the service reservoir to 
the application chamber. 

From what has been said, it will be plain that if the brake-pipe 
reduction is continued below the point at which the pressure and the 
reduction-limiting chambers equalize, the pressure in the pressure 
chamber can no longer continue to reduce in accordance with the 



AIR BRAKES 



151 



still falling brake-pipe pressure. This results in a differential being 
established between the pressure in the pressure (•hanil)er (and 
chambers D and E) and the brake-pipe pressure which, when the 
brake-pipe pressure is reduced below 60 pounds when carrying 110 
pounds brake-pipe pressure or below 35 pounds with 70 pounds 
brake-pipe pressure, is sufficient to cause the release piston to travel 
to its extreme (emergency) position and produce quick action and 
an emergency application of the brakes as will be explained under 
"Emergency Position". 

Releasing Action 

(a) Preliminary Release Position. Whether the parts are In 
service lap or over-reduction lap position, after an application has 
been made, an increase in brake-pipe pressure above that in the 



Equalizing Crad 
Spring 



Release (Srod 
Spring, rrr-r. Release 



Pressure Chamber 
Check Valve 



Eguolfzing 
Fi5ton-\ 



Eguoh'ring 
Grod. Valve' 



Reduction 

Limifing- 

ChamberEx. 

Equalizing 
Slide Valve 

Release 
Grad. Valve 



Equalizing 
Pi si on Slop 



Equalizing SlopSpnng rj^^^^t^c,radJiel^cap 




^Fipe 



rg. Slide Valve 



Sen Cgl. 
Emerg. Ci^l. Ex. 



Emerg. Kes. 
Fig. 125 Preliminary Release rosition for Westinghouse "3-E" Control Valve 

pressure chamber (chambers 7) and E) will cause the equalizing 
piston and its valves to return to the release positions described 
below. 

The equalizing piston moves before the release piston, the parts 
being designed to require a somewhat higher differential to move 
the release piston and its attached valves than is sufficient to move 
the equalizing piston. 



152 



AIR BRAKES 



In preliminary release position, Fig. 125, it will be noted that 
chamber E behind the release piston is connected by way of the 
equalizing shde valve and graduating valve to the reduction-limiting 
chamber exhaust. This connection is made but momentarily, in 
what may be considered the first stage of the movement of the parts 
to release position. It plays a very important part, however, in 
the release operation of the valve, since, by thus insuring a momen- 
tary but material drop in the pressure in chamber E below that in 
the brake pipe and in chamber B, the release piston is forced to 
return positively to its release position shown in Fig. 126 — secondary 
release position. 

In preliminary release position, the pressure chamber is con- 
nected by way of the equalizing slide valve to chamber F. The 



Spring^ 



Release Qrud 
Spring 



Pressure Chamber 
Check Valve 
X ChamjEx^ Ser. Cgl. E'k. 



£quc&izing 
Fislon" 



EqualiziriQ- 
urad. Valve 
Reduclion_ 
Limilinq 
Chambercx. 
Equaliz:ing- 
5lide Valve 
Release 
<^rad. Valve' 

Egualizwg 
Fiston Stop' 




Fosiiion forGrod. Release 



Ser. Cy 



Brake Ripe 
^Emerg. Slide Valve 

Emerg. Res. 



Fig. 126. 



Emerg. Cgl. £x. 
Secondary Release Position for Westinghouse "3-E" Control Valve 



pressure thus acting in chamber F, in addition to the force of the 
equalizing stop spring, serves to insure that the equalizing piston 
and its valves hesitate in preliminary release position for a sufficient 
length of time to reduce the pressure in chamber E, as already 
explained. 

It will be observed that the application piston is still in its lap 
position, holding the pressure in the service brake cylinder. This 
continues until the release of air from the application chamber and 



AIR BRAKES 153 

chamber C, which does not take place until the parts move to the 
next stage in the release movement — secondary release position. 
Fig. 126. 

In the movement of the equalizing slide valve to preliminary 
release position, the reduction chamber is connected to the reduc- 
tion-chamber exhaust port and the atmosphere, and so remains until 
the parts again move to over-reduction position or beyond. 

Although there are other connections made in the preliminary 
release position as shown in Fig. 125, they perform no particular 
function other than has already been described, and consequently 
do not need to be again referred to. 

(b) Secondary Release Position. In the movement of the 
parts to release position, the next stage, following the preliminary 
release position is called the secondary release position. Fig. 126. It 
will be seen from the illustration that the venting of the air from 
chamber E through the equalizing slide valve and graduating valve 
to the reduction-limiting chamber exhaust has resulted in the rela- 
tively higher brake-pipe pressure moving the release piston and its 
valves to their release positions, although for an instant the equaliz- 
ing piston and its valves still remain as shown in Fig. 125 — prelimin- 
ary release position. 

With the release piston and its valves in the position shown in 
Fig. 126, a connection is made from chamber F through the release 
slide valve to the emergency-piston exhaust. At the same time the 
pressure chamber is connected by way of the equalizing slide valve 
to the same port which connects chamber F to the atmosphere. 
This tends to maintain the pressure in chamber F temporarily so as 
to insure the connection from chamber E to the atmosphere being 
held open, as explained above, until the release piston and its valves 
are entirely back in their release positions. In so moving, however, 
the release slide valve is gradually increasing the size of the open- 
ing from chamber F to the atmosphere, until a point is reached 
where the pressure in chamber F is lowered sufficiently to permit 
the differential pressure already acting on the equalizing piston to 
start this piston toward its release position. The resulting move- 
ment of the equalizing slide valve restricts and finally stops entirely 
the flow of air from the pressure chamber to chamber F, the pressure 
in which is, therefore, rapidly exhausted to the atmosphere through 



154 



AIR BRAKES 



the ports already mentioned and the equalizing piston and its valves 
are then held positively in their release pQsition as shown in Fig. 127. 
Comparing Fig. 125 and Fig. 126, it will be noted that the move- 
ment of the release piston, slide valve, and graduating valve from 
the position shown in Fig. 125 to that shown in Fig. 126, opens com- 
munication from chamber E past the end of the release graduating 
valve, through the release slide valve and direct- and graduated- 
release cap and through the equalizing slide valve to the reduction- 
Hmiting chamber exhaust and atmosphere. This outlet from cham- 
ber E to the atmosphere is simply additional, it will be noted, to 



Equalizing Grad T^etease Grad Spring 

Sbrin^^^^^ ^<7uO/izing^^^^^^7). Release 

^ y B^H ^^.,/. T^„,_, ^nmu .p^-^f^^ 



fjpp. ChamEx- 5er. Cl/1. Ex. 3er. Res. 



Equalizing. 
Fisfon 

SerRes. ^ 

Charginq 
Valve 
Equalizing_ 

Gmd. Valve 
Reduclion 

Limiting 
Chamber Ek. 
Equalizing 
Slide Valve 
Release 
<Srad- Valve 

Equalizing 
Piston Stop 




\S rake Pipe 



Equalizincj Step Spring Direct l.6rad. Pel Cap/ ^mm^ va 

Fbsilion for Grad- Release ' Sen Cyl -^ jEmenq. Cyl 

£merg. Cyl. Ex. Emerg. Res 



'rg Slide Waive 



Fig. 127. Graduated Release and Release, Charging-Pressure Chamber Oniv for 
Westinghouse "3-E" Control Valve 

that already existing as explained in connection with Fig. 125, and, 
like it, is but momentary. In the succeeding position, Fig. 127, both 
these connections from chamber E to the atmosphere are cut off. 
^ The movement of the release graduating and slide valves to 
their release positions opens the application chamber and chamber 
C by way of the valves mentioned to the application-chamber 
exhaust and atmosphere. The resulting reduction of pressure in 
chamber C below that exerted by the application-piston spring and 
the air pressure in chamber M causes the application piston, with its 
attached valves, to move back to release position, Fig. 126, opening 
the service brake cylinder through the exhaust valve to the service- 



AIR BRAKES 155 

cylinder exhaust and atmosphere. The release of the brake is, 
therefore, commenced as soon as the release piston and its valves 
are returned to their release positions. 

While there are other connections shown in Fig. 120 besides 
those just explained, they perform no particular function, so far as 
the momentan' position of the parts in secondary release position. 
Fig. 126, is concerned, and will, therefore, not be referred to until all 
can be explained together under ''Graduated Release Position", 
Fig. 127. 

(c) Graduated Release Position. As already stated, the move- 
ment of the release slide valve to its release position connects cham- 
ber F to the emergency-piston exhaust and atmosphere, causing the 
equalizing piston and its valves to be moved to and held positively in 
their release positions. Fig. 127. 

It should be clearly understood that a very slight increase in 
brake-pipe pressure (about 1^ to 2 pounds) above that remaining 
in the pressure chamber is sufficient to move the parts through the 
successive momentary positions of preliminary and secondary 
release as just explained, until they reach their final positions shown 
in Fig. 127 — graduated release position. 

In this position (graduated release being assumed to be cut in), 
the application chamber and chamber C are open through the release 
slide valve and graduating valve to the application-chamber exhaust 
and atmosphere. So far as this connection is concerned, the release 
would be complete provided the parts did not move, but it will be 
noted that in this position also the emergency reservoir is connected 
by way of the equalizing slide valve, and the direct- and graduated- 
release cap (which is adjusted to give graduated release) through the 
release slide valve and past the end of the release graduating valve 
to chamber E. The pressure in the emergency reservoir is substan- 
tially that to which it was originally charged, namely, normal brake- 
pipe pressure. The pressure in chamber E, it will be remembered, 
was reduced equally with the pressure-chamber pressure when the 
brake application was made. Air from the emergency reservoir, 
at the higher pressure, will therefore flow into chamber E and, from 
chamber E by way of the equalizing slide valve, to the pressure 
chamber, at the lower pressure, and tend to increase the pressure in 
chamber E and the pressure chamber at the same time that the 



156 



AIR BRAKES 



brake-pipe pressure in chamber B is being increased. If the pres- 
sure in chamber E rises faster than that in chamber B, the higher 
pressure which will soon be built up in chamber E will tend to move 
the release piston and graduating valve over toward graduated- 
release lap position, Fig. 128, and either partially restrict or wholly 
stop the flow of air from the application chamber to the atmosphere, 
and from the emergency reservoir to chamber E. If the brake- 
pipe pressure is increased very slowly, the relatively rapid increase 
of pressure in chamber E may cause the release piston and graduat- 
ing valve to graduate the release as explained in connection with 



E'cfualizing Gnjd Tielease Grod Spring fipp. Chamber £x. 3er. Ties. 



Equalizing 
Fisfon- 



Efi/olizing 
Grad Valve— 
TfeducHon 
Limifinq 
ChamberEx. 



EquaUzing 
Slide Valve 

Fieleose^ 
■ Grad- Valve 

Equalizing^ 
Piston Slop 




Equalizinq Stop Spring jPirecfuGrvd. Rel. Cap 

PosiUon for Grad. Release Sen Cyi. 



\BrakePipe 



'^Emerq. Slide Valve 



Fig. 128. 



Emerg. Cul Ex . Emerq. Res- 
Graduated-Release Lap Position for Westinghouse "3-E" Control Valve 



Fig. 128. If the rate of rise of brake-pipe pressure is not slow enough 
to permit this action, the parts will move toward the position shown 
in Fig. 128 sufficiently to so restrict the flow of air from the emer- 
gency reservoir to chamber E as to adjust the rate of rise of pressure 
in chamber E to correspond to that of the brake pipe and chamber 
By in which case the release of air from the application chamber will 
be correspondingly prolonged. 

The escape of air from the application chamber and chamber 
C to the atmosphere, as already explained in connection with Fig. 
126, results in the application-piston spring and brake-cylinder 
pressure acting in chamber M moving the application piston with 



AIR BRAKES 157 

its valve back from their lap position, as shown in Fig. 125, to their 
release position, as shown in Figs. 125 and 127, in which position air 
from the brake cylinder is exhausted to the atmosphere by way of 
the exhaust valve and service-cylinder exhaust port. Whether the 
brake-cylinder pressure is entirely or only partially released depends 
upon whether the exhaust air from the application chamber and 
chamber C is partial or complete. This has already been referred 
to and will be further mentioned in connection with Fig. 128. It 
will be noted that in Figs. 125, 126, and 127, the reduction-limiting 
chamber is connected to the reduction-limiting chamber exhaust and 
atmosphere through the equalizing slide valve, and that in Figs. 
12G and 127 chamber 8 is connected through the release slide valve 
to the emergency-piston exhaust and atmosphere, so that the air in 
these chambers is completely exhausted to the atmosphere when 
either a graduated or direct release is made. 

Referring to Fig. 127, it will be noted that chamber E is con- 
nected to chamber A" and that air from the emergency reservoir has 
access to chamber G. These connections being opened by the 
movement of the equalizing slide valve to its release position, w^hether 
or not the service-reservoir charging valve will be opened and permit 
the re-charging of the service reservoir to begin at once will depend 
on the relative pressures in the pressure chamber and emergency 
and service reservoirs.. With the ordinary manipulation of the 
brake, the service-reservoir charging valve will remain closed. Fig. 
127, preventing the air from the emergency reservoir reaching the 
service reservoir, and the pressure chamber only will be re-charged 
until its pressure has been increased to within about 5 pounds of 
that in the emergency reservoir. 

As already indicated, if the brake pipe is fully re-charged without 
a graduation of the release being made, the parts will remain in the 
positions shown in Fig. 127 and the release will be complete and with- 
out graduations. The only change which takes place while such a 
release is being made is the movement of the service-reservoir charg- 
ing valve from the position shown in Fig. 127 to that shown in Fig. 
118, which should properly be regarded as illustrating the final 
stage in the re-charging of the equipment of which ¥\g. 127 illustrates 
the initial stage. That is to say, at first the pressure chamber alone 
is re-charged and this re-charge is accomplished from the emergency 



158 AIR BRAKES 

reservoir only, without any air being drawn for this purpose from 
the brake pipe. The air which is supphed through the brake valve 
to the brake pipe is, therefore, given every possible advantage and 
opportunity to accomplish what is intended when the brake-valve 
handle is moved to release position, namely, to release the brakes 
by causing an increase of pressure sufficient to accomplish this, 
throughout the entire length of the brake pipe. After the release 
has been thoroughly established in this manner, the re-charging of 
the reservoirs to their original pressure takes place as explained in 
connection with Fig. 118. 

(d) Release Lap Position. If, however, the brake-pipe pres- 
sure is not fully restored, a graduation of release being made, that is, 
if the brake pipe is partially re-charged and the brake-valve handle 
then returned to lap position, the continued flow of air from the 
emergency reservoir to pressure chamber and chamber E will tend 
to increase the pressure in the pressure chamber and chamber E 
above that of chamber B which is now stationary, causing the release 
piston and graduating valve to move over until the shoulder on the 
end of the release piston stem comes in contact with the release 
slide valve. Fig. 128. This closes the^xhaust from the application 
chamber to the atmosphere and prevents further flow of air from 
the emergency reservoir to the pressure chamber and chamber E. 

The flow of air from the service brake cylinder to the atmos- 
phere (continuing as explained in connection with Fig. 127), will at 
once reduce the pressure in chamber M below that now retained in 
chamber C by the small amount which is sufficient to cause the 
application piston to move over to the position shown in Fig. 128, 
in which the exhaust valve is closed, thus preventing further release 
of air from the service brake cylinder. The other connections 
remain as already explained 

(e) Release and Charging Pressure Chamber and Emergency 
and Service Reservoirs. The gradual release of brake-cylinder pres- 
sure may be continued as explained above. Fig. 128, until the pres- 
sures in the emergency reservoir and pressure chamber have become 
equal. On account of the relatively large volume of the emergency 
reservoir compared with that of the pressure chamber, this equaliza- 
tion will not take place until the pressure chamber has been re- 
charged to within about 5 pounds of the brake-pipe pressure carried. 



AIR BRAKES 



159 



Beyond this point, whatever small amount of pressure may remain 
in the service brake cylinder is released entirely and the emergency 
and service reservoirs, as well as the pressure chamber, are re-charged 
from the brake pipe as described in connection with Fig. 128. 

(f) Direct Release and Charging Position. Up to this point, 
the direct- and graduated-relcase cap lias been assumed to be in the 
position for graduated release. Fig. 129 corresponds to Fig. 127, 
except that the direct- and graduated-release cap is adjusted for 
direct release. It will be noted that there is now no connection from 
the emergency reservoir to the pressure chamber or chamber E. 
Consequently the pressure chamber is being re-charged only by air 



If el ease i^rad Spring 
Spring ^^ Equalizing -^ Release 

Check, Vji ve 



Egualizing Qrad 



Sen Res. 



Equohzing^^^ 
fusion 

5er. Res 

CharginqValve 

Equalizing. 

Orad Valve 

Reduction 

Limit wq 

Chamber E^. 

Equalizing^ 

Slide Valve 

Release ^\ 
Grad Valve 

r — - 

Equalizing 
Piston Slop 




\b rake Ripe 



EguolizingSfopSpring direct KGnad.RelLop\ ' ^^'^ry'-g ^ ■ ~ 

Position for Direct Release SerCgl f Em erg Cyl 
Em&r^.CijlEyf.' 



Emery. Slide Valve 
'.merg.Res., 



Fig. 129. Direct Release, Charging Pressure Chamber Only, for Westinghouse "3-W" 

Control Valve 

from the brake pipe going through feed groove i to chamber E, and 
thence by way of the equalizing slide valve to the pressure chamber. 
The pressure in chamber E cannot, therefore, increase above that in 
chamber 5, and the release piston, graduating valve, and slide valve 
remain in the position shown in Fig. 129. 

With the direct- and graduated-release cap adjusted for direct 
release, it will be noted from Fig. 129 that the application chamber 
and chamber C are open through the release slide valve to a port 
connecting through the direct- and graduated-release cap to the 
application-chamber exhaust and atmosphere. This affords an out- 



160 



AIR BRAKES 



let from the application chamber to the atmosphere which cannot 
be closed as long as the release slide valve remains in the position 
shown, even though the release piston and graduating valve should, 
from any cause, be moved back so that the release graduating valve 
would partially or entirely restrict the application-chamber release 
port, which is also shown to be open through the release graduating 
valve in Fig. 129. Moreover, it will be noted that there are two 
outlets from the application chamber to the atmosphere when the 
valve is adjusted for direct release as compared with one when 
graduated release is cut in. 

Emergency Position 

(a) Quick=Action Valve Venting. When the brake-pipe pres- 
sure is reduced faster than at the predetermined rate for service 

Ifeleo5e Orad 



CquaUzing Grpd. 
Spring 



Pressure Chamber 
Check Valve 



Equalizing 
- Piston — 



Equalizing 
(Srad. Yah 



Egualizing __ 
Slide Valve 



Release 
Slide Valve 

Equalizing- 
Piston Stop 



Sen Pes. 

Pressure Chamber 




, Emeng-PislonEx.. , _. 

Equalizing Stop Spring Direct uGradRel Cap 



^merg. Slide 
Valve 



SenCgl. '^ f ^Emeng. Cyl. \ Ouicl^ftclionEx. 
Emerg. C<^1 £>. Emerg. Res. 



Quick ftchon Valve 



Fig. 130. Emergency Position, Quick-Action Valve Venting, for Westinghouse "3-E 

Control Valve 

applications, or if the brake-pipe reduction should be continued 
below the point at which the pressure and reduction-limiting cham- 
bers equalize (as explained under * ^Over-Reduction Position"), the 
differential pressure acting on the release and equalizing pistons 
becomes sufficient to move them to their extreme or emergency posi- 
tions. Fig. 130. 

In this position, air from the emergency reservoir flows directly 
to chamber E and from chamber E to the under side of the quick- 



AIR BRAKES 101 

action closing valve. Chamber T, above the quick-action closi-ng 
valve, is connected to the emergency brake-cyHnder port in which 
there is no pressure, even though a full-service application of the 
brakes may have just preceded the emergency application. 

The higher pressure on the under side of the quick-action closing 
valve, therefore, raises this valve and air flows to chamber W above 
the quick-action piston, forcing the latter down and opening the 
quick-action valve against brake-pipe pressure in chamber Y. As 
soon as the quick-action valve is unseated in this manner, air from 
the brake pipe flows past the quick-action valve to the quick-action 
exhaust and atmosphere, causing a local venting of brake-pipe air 
and transmitting the quick application serially throughout the train. 

Air from the emergency reservoir flowing to chamber E also 
flows directly to the application chamber and chamber C, which 
forces the application piston and its valve over into their extreme 
positions, opening the service reservoir through the application slide 
valve and chamber to the service brake cylinder, thus permitting 
the pressures in the service reservoir and service brake cylinder to 
equalize. ^ 

At the same time chamber P, above the large emergency piston, 
is connected through the release slide valve to the emergency-piston 
exhaust and atmosphere, permitting the emergency-reservoir pres- 
sure in chamber R to force the emergency piston and its slide valve 
upward to their emergency positions. 

In this position of the emergency parts, the emergency reservoir 
is connected past the end of the emergency slide valve to the emer- 
gency brake cylinder, thus permitting the pressures in the emergency 
reservoir and brake cylinder to equalize. Chamber R is also con- 
nected through the emergency slide valve to the service cylinder 
port, which permits equalization of the service and emergency reser- 
voirs and brake cylinders. 

It will be noted that in this position the emergency slide valve 
opens a port which connects chamber M, behind the application 
piston, through the emergency slide valve to emergency cylinder 
exhaust. This, in connection with the admission of air from the 
emergency reservoir to the application chamber and chamber C, as 
already explained, still further insures a quick and positive move- 
ment of the apphcation piston and its valves to emergency position. 



162 



AIR BRAKES 



In this position the pressure chamber is connected through the 
equaHzing sHde valve to chamber D, The pressure chamber is also 
connected past the pressure-chamber check valve to chamber E, 
and chamber D is connected past the end of the equalizing graduat- 
ing valve through the equalizing slide valve to the reduction-limiting 
chamber. 

(b) Quick=Action Valve Closed. The emergency brake-cylin- 
der pressure and the pressure in chamber T above the quick-action 
closing valve continue to rise and the pressure in the emergency 
reservoir and in chamber W below the quick-action closing valve 
falls, as explained above, until these pressures become substantially 






Fie lease O^od 



Piston 
Release drad. 
Valve 

Equalizing 

Qrad Valve 

Release . 

5lide Valve 

Equallzng 

5lide Valve 

Equalizing 
Pi 5t on Stop 



Pressure Chamber Chech Volve. 

■056 Pi 5 ton / ySerPes. 




Equalizinq Slop3prinq 



\ Drahe 
Pipe 



Direct &.anodFe}.Cqp / / \ \\ , 

Emer Piston ^ 5/^rCi^l'. \EmerQ^l> 

Emer^lideVolve'^^ EmerCif/ Ex CmerHes. 



nch PIction Valve 



Fig. 131. Emcrsency Position, Quick-Action Valve Closed, for Westinghouse "3-E" 

Control Valve 

equal. This equalization of the pressures on the opposite sides of 
the quick-action closing valve permits its spring to return the valve 
to its seat, cutting off further flow of air to chamber W. Chamber 
W is connected through the leakage hole in the quick-action piston 
to chamber X so that as soon as the quick-action closing valve is 
seated, the pressure in chamber W expands through this leakage hole 
to chamber X and the atmosphere through the quick-action exhaust 
opening. The balancing of the pressures in chambers X and W 
thus permits the quick-action valve spring to return the quick- 
action valve to its seat, closing the outlet from the brake pipe to the 



AIR BRAKES 



163 



atmosphere, Fig. 131. This insures against an escape of air from 
the brake pipe to the atmosphere when a release is made following 
the operation of the quick-action parts. 

Except for the closing of the quick-action valve and return of 
the quick-action parts to normal position, the positions of the other 
parts of the valve and connections between the various reservoirs 
and cylinders, etc., remain as already explained in connection with 
Fig. 130. 

When releasing after an emergency application, as soon as the 
brake-pipe pressure in chambers .1 and B is increased above that 
which remains in chambers D and E, the parts will move to their 
release positions, exliausting the air from the brake cylinders and 
re-charging the reservoirs and pressure chamber as explained under 
''Release and Re-Charging", Figs. 125, 126, 127. 





22 






5^ 7' 10 



l) 



Fig. 132. Diagrammatic Section of Brake Cylinder 

Fig. 132 illustrates the tx-pe of brake cylinder employed, two of 
which are used on each car. As previously explained, one brake 
cylinder is used during service application and both in emergency 
applications. 

INSTRUCTIONS FOR OPERATING "PC" PASSENGER 
BRAKE EQUIPMENT 

The following suggestions are given by the builders for the 
general handling of the 'TC" Passenger Brake Equipment. 

The brake should be handleil by the engineers in the same manner as with 
cars equipped with quick-action triples, the only difference being that an emer- 
gency apphcation will be obtained should a service reduction of the brake-pipe 
pressure be continued below 60 pounds when carrying 110 pounds pressure 
or below 35 pounds with 70 pounds brake-pipe pressure. 

When it is found necessary' to cut out the brake, close the cut-out cock 
in the crossover pipe and bleed both the service and emergency resers'oirs. 



164 AIR BRAKES 

Should it become necessary to bleed the brake when the engine is detached, 
or air connection is not made, first bleed the brake pipe and then bleed both 
the service and the emergency reservoirs. 

The two sets of cylinder levers are connected to the same truck pull rods 
as stated above. Therefore, when a service application of the brake is made, 
the push-rod end of the emergency-cylinder lever will move the same distance 
as the push-rod end of the service-cylinder lever, but the crosshead being slotted, 
the piston of the emergency cylinder will not move. Consequently, the fact 
that the emergency-cylinder crosshead is in release position does not indicate 
that the air brakes are released. To determine this, look at the ends of either 
the service- or emergency-cylinder levers. 

Whenever it is necessary to change the adjustment of the automatic slack- 
adjuster, it is imperative that the crossheads of the two adjusters be left at 
the same distance from their respective brake-cylinder heads, in order that 
the piston travel of the two cylinders in emergency application will be the same. 

The various exhaust openings referred to in the following are plainly 
marked on the outline drawings. 

The quick-action exhaust is the one-inch opening in the bottom of the 
control-valve reservoir. Should there be a continual blow at this opening, 
make an emergency application and then release; if the blow continues, remove 
the quick-action portion and substitute a new or repaired portion or repair 
the quick-action valve seat, which will be found defective. The quick-action 
portion is at the left hand when facing the equalizing portion. 

There are three control-valve exhaust openings — two on the equalizing 
portion and one on the side of the control-valve reservoir, all tapped for f-inch 
pipe. 

Should there be a blow at the application-chamber exhaust (|-inch exhaust 
opening on side of the control-valve reservoir) with the brakes applied or released, 
it indicates a defective equalizing portion, and a new one, or one that has been 
repaired, should be substituted. 

Should there be a blow at the reduction-limiting chamber exhaust (f-inch 
exhaust on left side of equalizing portion) in release or service position, it indi- 
cates a defective application portion, and a new one, or one that has been re- 
paired, should be substituted. This portion is located back of the equalizing 
portion inside the reservoir. If the blow occurs only after 30 pounds brake-pipe 
reduction, it indicates a defective emergency-reservoir check valve (the middle 
check valve in the equalizing portion) and a new one, or one that has been 
repaired should be substituted. If the blow does not cease, it indicates a de- 
fective equalizing portion, and a new one, or one that has been repaired, should 
be substituted. 

Should there be a blow at the emergency-piston exhaust (f-inch exhaust 
on the right-hand side of the equalizing portion), make a 15-pound brake-pipe 
reduction and lap the brake valve. If the blow ceases, it indicates that the 
emergency piston is defective, and a new portion or one that has been repaired, 
should be substituted. If the blow does not cease, it indicates that the equalizing 
portion is defective, and a nsw one, or one that has been repaired, should be 
substituted. 

A hard blow at the service brake-cylinder exhaust (tapped for f-inch pipe 
and located at the left side of the control-valve reservoir) with the brakes applied 
indicates that the application portion is defective, and a new one, or one that 
has been repaired, should be substituted. This portion is located back of the 
equalizing portion inside the reservoir. If this blow occurs when the brakes 
are released, it indicates either a defective application or emergency portion, 



AIR BRAKES 165 

and a now ono or a ropaired portion, as found to be rcqiiirod on invostip;ation, 
should bo substituted. 

A hard blow at the cmorjijoncy-oylindcT exhaust (tap{)od for .^-inch pii)0 
and located on the bottom of the eontrol-valve reservoir) with th(^ l)rakes either 
applied or rc^leased indicates a defe(!tive emergency i)ortion, and a new one, or 
one that has been repaired, should be substituted. 

If the trouble described in the five paragraphs immediately preceding is 
not overcome by the remedies therein suggested, remove; the application i)ortion 
and examine its gasket, as a defect in same may be the cause of the difliculty. 

When removing the application, emergency, and quick-action portions, 
their respective gaskets should remain on the reservoir. On removing the equal- 
izing portion, its gasket should remain on the application portion, except when 
the application portion is shipped to and from jjoints where triple valves are 
cared for. 

When applying the different portions, the gaskets should be carefully 
examined to see that no ports are restricted, and that tlu; gasket is not defective 
between ports. See also that all nuts are drawn up evenly to prevent uneven 
seating of the parts. 

On the front and at the center of the equalizing portion is located the 
direct- and graduated-release cap (held by a single stud) on which is the j^ointer. 
The position of this pointer indicates whether the valve is adjusted for direct 
release or graduated release. This cap should be adjusted for either direct or 
graduated release according to the instructions issued by the railroad. 

Recent Improvements in Brake Equipment. In addition to the 
different brake equipments described, mention might be made of 
two other equipments which have just recently been tried out. 
One of these is the Westinghouse Electro-Pneumatic Brake Equip- 
ment with the Type *'U" standard universal valve, for use in 
passenger service. The other is the Empty and Load Freight Brake 
Equipment. The results of tests conducted on each of these equip- 
ments has been satisfactory in every way, but the apparatus has not 
at the present time been very widely used. 

WESTINGHOUSE TRAIN AIR=SIGNAL SYSTEM 

Essentials of Air=Signal System. A train signal system is very 
essential in maintaining fast schedules with passenger trains, its 
object being to furnish a means of communication between the 
trainmen and enginemen. The most common form used is the 
pneumatic, and is made up of the following principal parts: 

(1) A I -inch signal pipe, which extends throughout tlie length of 
the train, being connected between cars by flexible hose and 
suitable couplings. 

(2) A reducing valve, which is located on the engine, and wliich 



166 



AIR BRAKES 



feeds air from the main reservoir into the signal pipe at 40 
pounds pressure. 

(3) A signal valve and whistle, ^feftCS^L'^'^^'"^ ^'>^/' 
located in the cab and con- 
nected to the signal pipe. 

(4) A car discharge valve, lo- 
cated on each car and con- 
nected to the signal pipe. 
The action of the signal 

system is automatic. If an acci- 
dent happens to the train which 
breaks the signal pipe, the pres- 
sure in the signal pipe is reduced 
and the whistle in the cab blows 
a blast. The trainmen may also 
signal the enginemen by opening 
the car discharge valve, which reduces the pressure in the signal 




Fig. 133. Section through Reducing Valve 
in Westinghouse Air-Signal System 



To W/7istle. 




Fig, 134. Section through Signal Valve in Westinghouse Air-Signal System 



pipe, thus operating the signal valve in the cab and blowing the 
whistle as before. The operation of the various parts is as follows : 



AIR BRAKES 



167 




Reducing \ ahe. The reducing valve, a section through which 
is shown in Fig. 133, is located in a suitable place on the locomotive. 
Its purpose is to receive air from the main reser\-oir and feed it into 
the signal pipe, maintaining a pressure of 40 pounds, ^^^len no 
air is in the system, the parts occupy the position shouTi, but when 
air is admitted from the main reservoir, it flows through the passage 
A and the supply valve 1, into the chamber B and out through the 
port C into the main signal pipe. Wlien the air in the main signal 
pi[je attains a pressure of 40 pounds, the pressure in 
the chamber B, acting on the piston 2, forces it 
downward and compresses the spring 3. This pemuts 
the spring 4 to close the supply valve 1. No more 
air can then enter the signal pipe until its pressure 
^jecomes reduced so that the spring 3 will force the 
piston 2 upward and lift the supply valve 1. T^-pe 
*'C-6*' rediK-infT valve, Fig. 36, is also used. 

Signal \ alve. The signal valve. Fig. 134, con- 
trols the supply of air to the whistle, a reduction of 
air pressure in the signal pipe admitting air to the 
whistle through the signal valve. The two compart- 
ments .4 and B are diWded by the diaphragm 1 to 
which is attached the stem 2. This stem is milled 
triangular in section from the lower end to the pe- 
ripheral groove 3 but above the groove 3 it fits the 
bushing 4 snugly. The lower end of the stem 2 acts as 
a valve on the seat 5. Air enters the signal valve 
from the signal pipe, through the passage C, passing through the 
small port D into the chamber A, and through the passage £, around 
the triangular portion of the stem 2, into the chamber B. This 
charges the chambers A and B to the signal-pipe pressure. A 
sudden reduction in signal-pipe pressure reduces the pressure in 
the chamber A; and the diaphragm 1, acted on by the pressure in 
the chamber B, rises, lifting the stem 2 and momentarily permitting 
air to pass from the signal pipe to the whistle, Fig. 135. The result- 
ing blast of the whistle is a signal to the enginemen. This same 
reduction of pressure in the signal pipe causes the reducing valve 
to re-charge the system. The pressures in the chambers .1 and B 
equalize quickly, and the lower end of the stem 2 returns to its seat. 




Fig. Vi-'j- -"i^^^i^l 

Wrostle in We=t- 

inghouse Air- 

Sicnal System 



168 



AIR BRAKES 



Car Discharge Valve. The car discharge valve, Fig. 136, is 
usually located outside the car above the door or under the roof of 
the vestibule, in such a position that the 
signal cord passing through the car can 
easily be fastened to the small lever of the 
valve. The valve is connected to a branch 
pipe which extends from the signal pipe. 
The signal cord is connected to the eye in 
lever 1. Each pull in the signal cord 
causes the lever 1 to open the check valve 
2, permitting air to escape from the signal 
pipe. This causes a reduction in the signal r-fi 
pipe, which, in turn, causes the whistle to 
blow as previously described. The spring 
3 closes the valve 2 when the signal cord 
is not held. 

For the successful operation of the 
signal system, the signal pipe must be per- 
fectly tight. Care must be exercised in 
using the car discharge valve so that suf- 
ficient time is permitted to elapse be- 
tween successive discharges. ^.^ 136 section . through Car 

Discharge Valve in Westing- 
house Air-Signal System 

BRIEF INSTRUCTIONS FOR THE USE AND CARE 
OF AIR=BRAKE EQUIPMENT 

The following instructions apply more directly to the old types 

of passenger and freight brake equipments, applying only in a 

general way to the later improved types. 

Train Inspection. When a train is made up at a terminal, the air hose 
should all be coupled and the angle cocks all opened except the one at the rear 
end of the last car. The brake pipe should then be charged to about 40 pounds, 
in order that the inspector may examine for leaks. When the brake pipe has 
been fully charged, the engineer should apply the brake by making a light 
reduction in the brake pipe, which should then be followed by a full-service 
application. He should note the time required in making these reductions, 
in order to be assured that all pistons are moved past the leakage groove when 
the train is out upon the road. The engineer, after making the full reduction, 
should leave his brake valve in lap position until the inspector has examined 
the brake under every car. It should be the duty of the engineer to see that 
the brake equipment on the locomotive is in proper working order. 




AIR BRAKES 169 

Running Test. In passenger service, when a locomotive has been changed 
or a train made up, the engineer should mak(^ a running test within a mile of 
the station, as follows: A brake-pipe r(ulu(;tion of about 5 pounds should be 
made. If the brakes arc felt to be applying and the time of the discharge is 
proportional to the numl^er of cars in the train, the engineer will conclude that 
the brake is in j)roper working order. It is well, also, to make this test on 
approaching hazardous places. 

Sendee Applieations. In making a service application of the brakes, the 
first reduction should be about 5 j)Ounds on a train of cars 30 or less, and about 
7 pounds on a train exceeding 30 cars. This will insure the travel of all pistons 
beyond the leakage groove. Subsequent reductions of from two to three pounds 
can be made to increase the braking power, if desired. A reduction of 25 to 
30 pounds will make a full-service application. 

In stopping a passenger train, at least two applications should be used; 
the first should reduce the speed of the train to about 8 miles an hour, when the 
train is within two or three car lengths of the point at which the train is to be 
stopped. Moving the brake-valve handle to release position for only sufficient 
time to release all brakes, then returning it to lap position, will make it possible 
for a second light application to stop the train. Just before all stops of passenger 
trains, except exact-position stops at water stations and coal chutes, the brakes 
should be released to avoid shocks to passengers. This release should be made 
on the last revolution of the drivers. If it should be made too soon and the 
train keep on moving, the engineer's brake valve should be moved to service 
position until the train stops. 

In making stops of freight trains, the best practice is to shut off the steam 
and allow the slack to run in before applying the brakes. The stop should be 
made with one application of the brakes. After the first reduction is made, if 
there are any leaks in the brake pipe, the braking force will be increased, and 
any subsequent reduction should be made less, in order to make up for these 
leaks. In stopping a long freight train at water stations and coal chutes, it 
is best to stop short of the place, cut off, and run up with the locomotive alone. 

On a freight train, where the locomotive is not equipped with the straight 
air brake or the "ET" equipment, the brakes should not be released when the 
speed of the train is 10 miles per hour or less. If this is done, the brakes in the 
front of the train may release, and, as the slack runs out, the train may part. 
If the locomotive is equipped with straight air or "ET" equipment, the train 
brakes can be released after the locomotive brakes are set, without danger of 
parting the train. 

Emergency Applications. The emergency application should never be 
used, except in case of an emergency. If the necessity arises, an emergency 
application may be made after a service reduction of about 15 pounds. In 
case an emergency is caused by the train parting, hose bursting, or the conductor's 
valve being opened, the engineer should place his valve on lap, in order to save 
the main-reservoir air. 

Use of Sand. The use of sand increases the braking power of a train and 
should be made in emergency stops. If 'sand is useil in service stops, it should 
be supplied some time before the brakes are applied in order to have sand under 
the entire train. If, for any reason, the wheels should skid, do not apply the 
sand as it will produce flat spots on the wheels. 



170 AIR BRAKES 

Pressure Retaining Valve. In holding trains on grades, a part or all of 
the retaining valves are set to maintain air pressure in the brake cylinder. If 
only part are set, those in the front of the train should be used. 

Backing Up Trains. In backing up long freight trains, the train should 
be stopped by the hand brakes on the leading end of the train, for the reason 
that if air were used, the brakes would apply on the cars near the engine and 
the leading cars might cause a break-in-two. 

In backing up a passenger train, where the train is controlled by a man on 
the leading car by means of an angle cock, the engineer's valve should be in 
running position. This gives the man on the rear of the train full control of 
the brakes. As soon as the engineer feels the brake apply, he should place his 
valve on lap. 

Double-Heading. When two or more locomotives are coupled in the same 
train, the brakes are operated by the leading locomotive. The cut-out cocks 
in the brake pipe just below the engineer's valve on all locomotives but the 
first should be closed. The pumps on all engines should be kept running. 

Conductor's Brake Valve. A conductor's brake valve is located on each 
passenger car. The purpose of this valve is that the conductor may stop the 
train in case of emergency; if the engineer's brake valve should fail to operate, 
he may signal the conductor to apply the brakes by opening the valve. 

Use of Angle Cocks. In setting a car out of a train, first release the brakes, 
then close the angle cock on both sides of the hose to be disconnected, and finally 
disconnect the hose by hand. Before leaving a car on the side track, the air 
brakes should first be released by opening the release valve on the auxiliary 
reservoir; and if the car is on a grade, the hand brake should be set. 

The angle cock should not be opened on the head end of a train while the 
locomotive is detached. When connecting a locomotive to the train that is 
already charged with air, the angle cock at the rear of the tender should be 
opened first to allow the hose to become charged and thus prevent a slight 
reduction in the brake pipe, which might set the brakes. All angle cocks upon 
charged brake pipes should be opened slowly. 

Cutting Out Brakes. If the brake equipment on any car is defective, it 
may be cut out by closing the cut-out cock in the branch pipe leading from the 
brake pipe to the triple valve. The release valve on the auxiliary reservoir 
should be opened to discharge the air. Never more than three cars with their 
brakes cut out should be placed together in a train on account of the emergency 
feature being unable to skip more than this number. 

Air Pump. The air pump should be run slowly with the drain-cocks 
open until the steam cylinder becomes warm and sufficient air-pressure has been 
attained to cushion the air, after which time the throttle may be fully opened. 
The lubricator should be in operation as soon as possible after starting, and the 
swab on the piston rod should be kept well oiled. The air cylinder should 
receive oil each trip. Valve oil should be used, and it should be inserted through 
the oil cup provided for that purpose, and not through the air strainer. 

Engineer's Brake Valve. With the handle in running position, the main- 
reservoir pressure should be maintained at 90 pounds or as high as needed, 
and the brake pipe at 70 or 110 pounds, depending on the system. This requires 
that the springs in the pump governor and feed valve must be carefully adjusted 
and that no leaks exist between ports in the rotary valve. The rotary valve 



AIR BRAKES 171 

should be cleaned and oiled when necessary; and if leaks exist, the valve should 
be scraped to a fit. 

Triple Valve and Brake Cylinders. The triple valve and brake cylinders 
should receive an occasional cleaning and oiling in order that they may be relied 
upon to fulfill their function. In cleaning the cylinder, special attention should 
be given to removing any deposit in the leakage groove. The walls of the cylinder 
should be coated with suitable oil or grease, and all bolts in the cylinder head 
and follower should be kept tight. 

In cleaning the triple valve, a common practice is to place the removable 
parts in kerosene until the other parts and the brake cylinder have been cleaned. 
The parts are then removed, cleaned, oiled, and replaced. Special care should 
be given to the slide valve and its seat, and to the graduating valve. All lint 
should be removed before replacing the parts. The piston packing ring should 
never be removed, except for renewing. A few drops of oil is all that is necessary 
for lubricating the entire triple valve. No oil should be permitted to get upon 
the gaskets or rubber-seated valve. The graduating-valve and check-valve 
springs should be examined and, if necessary, renewed. 



AIR BRAKES AS APPLIED TO ELECTRIC CARS 

GENERAL SURVEY OF SYSTEMS DEVELOPED 

That electric street cars and interurban cars should be equipped 
wdth reliable and efficient braking apparatus is a well-established 
fact, which is emphasized by the frequency of accidents on roads 
where poorly constructed braking appliances are used. The modern 
electric car is several times heavier than cars used a decade ago and 
speeds have increased remarkably, yet we frequently find cars fitted 
with braking apparatus but little better than that used in the days 
of the horse car. Of recent years, the most progressive roads have 
given much attention to the construction of their equipment in order 
to insure the safety of their passengers and, as a result, braking 
appliances have been greatly improved. 

Hand Brakes. The hand brake was the first form of brake 
used on electric cars and is still used in many of the smaller cities. 
It is also found today on many cars fitted with air brakes, to be used 
in case of necessity. The early forms of hand brakes consisted of a 
brake staff located at either end of the car, having a chain connected 
to the lower end of the staff. As the handle turned, the chain was 
wound up on the staff, and the resulting motion actuated the rods 
and levers which brought the brake shoes in contact with the wheels. 



172 



AIR BRAKES 



An improved form of brake staff is shown in Fig. 137. Here the 
winding drum takes the form of a spiral cam. In operation, the 
slack in the chain is quickly taken up and a very great braking 
pressure can be obtained. 

Early Forms of Air Brake. The first form of air brake installed 
on electric cars was known as the straight air-brake system. It is 
largely used today, as is also the automatic air-brake system. The 

straight air-brake system is usually 
found on trains of not more than 
one or two cars in length. Since 
electric roads do not, at this time, 
interchange cars to any great extent,' 
there is no very great necessity of 
interchangeable air-brake apparatus. 
As a result, there are a number of 
different types and makes of air- 
brake apparatus found in use on 
electric cars. All operate upon prac- 
tically the same general principles. 
Characteristics of Modern Sys= 
terns. The Westinghouse Company, 
in order to meet the requirements 
of the different classes of electric 
car service, has developed the follow- 
ing different brake equipments: (a) The ^^SM-l'' Brake Equipment; 
(b) the "SM-3" Brake Equipment; (c) the ^^S:ME'' Brake Equip- 
ment; (d) the ^^AMS" Brake Equipment; (e) the ^'AMM" Brake 
Equipment; (f) the ''AMR" Brake Equipment; and (g) the ''EL" 
Locomotive Brake Equipment. 

"SM-r and ",SJ/-5" Brake Equipments. Both the "SM-1" 
and "SM-3" brake equipments are straight air equipments, designed 
only for use on cars operated as single units. The two systems cover 
the air brake in its simplest form and are not considered satisfactory 
or safe for use on trains of more than one car in length. 

''SME" Brake Equipment. This is a straight air-brake equip- 
ment having an automatic emergency feature by means of which the 
simplicity of the straight air brake is retained for service operation, 
but it also has the additional protection afforded by the automatic 




Fig. 137. Hand Brake for Electric Cars 



AIR BRAKES 173 

application of the brake in case of a break-in-two or the bursting of 
a hose. It is designed for use on trains of not more than two cars 
in length. 

"AMS'' Brake Equipment. The ''A]MS" equipment is designed 
for use on cars running either singly or in not more than two-car 
trains, in city or slow-speed service. It combines the safety features 
of an automatic brake with the ease and flexibility of manipulation 
of the straight air system. A simple form of plain triple valve is 
used, having a quick re-charging feature. 

"AAIM'' Brake Equipment. The "AMM" equipment is con- 
structed for use on cars operated in trains of not more than three 
cars in length. It is especially well adapted for both city and high- 
speed interurban service. It is designed to provide for quick and 
flexible operation of the brakes on a single car unit by the straight 
air-brake system with the added feature of an immediate change to 
automatic brake operation whenever two or three cars make up 
the train. 

*'AMR'' Brake Equipment. The "AINIR" equipment is designed 
for use on trains of not more than five cars in length. It is designed 
for either city or high-speed interurban service and is strictly an 
automatic brake system. This equipment possesses such advan- 
tages as quick service, emergency, graduated release, and quick 
re-charging features. 

"EU' Locomotive Brake Equipment. The development of the 
modern high-power electric locomotive for handling both freight and 
passenger traffic at terminals and for service on electrified steam 
railroads created a demand for a thoroughly reliable and efficient 
brake which would embody the desirable features of the Westing- 
house No. 6 *'ET" equipment. Accordingly the No. 14 ''EL" 
locomotive brake equipment was developed, which is an adaptation 
of the No. 6 "ET" equipment to the conditions of electric service. 
The important and general features of this equipment may be 
obtained by reference to the description of the *'ET" equipment, 
pages 110 to 132, Part II. 

As the space allotted to this subject is limited, only one electric 
car system will be described — the ^Yestinghouse "SME" brake 
equipment. This system is chosen because it represents in a 
general way many systems now in common use. 



174 AIR BRAKES 

DETAILS OF "SME" BRAKE EQUIPMENT 

Features of "SME" System. As previously mentioned, this 
equipment is essentially a straight air-brake equipment having 
an automatic emergency feature. The simplicity of the straight 
air brake is available for ordinary service operation, while the addi- 
tional safety features of the automatic application of the brake is 
provided in case of a break-in-two, bursting of a hose, etc. The 
system is designed for use on trains of not more than two cars in 
length. The chief features of the equipment when using the Type 
*'D" emergency valve, as set forth in the manufacturer's pamphlets 
are as follows : 

(a) Straight air operation for service stops. 

(b) Brake cylinder release operates locally, i.e., through the emergency valve 
on each car. 

(c) Prompt service application and release operations due to design of the 
emergency valve. 

(d) Automatic maintenance of brake cylinder leakage. 

(e) Uniform brake cylinder pressure, independent of variations in piston travel 
or leakage. 

(f) Practically uniform compressor labor insured without the necessity of a 
governor S3'nchronizing system. 

(g) Automatic application of the brakes in case of ruptured piping, burst hose, 
or parting of the train. 

(h) Retarded release after an emergency application, as a penalty to discourage 

the unnecessary use of this feature, 
(i) One size of emergency valve for any size of brake cylinder, 
(j) Possibility of conductor setting the brakes in emergency by means of 

conductor's valve. 

Principal Working Parts. The system is composed of the 
following principal parts, which are located on the motor car : 

(a) A motor-driven air compressor which furnishes the compressed air for use 
in the brake system. 

(b) An electric compressor governor which automatically controls the opera- 
tion of the compressor between predetermined minimum and maximum 
pressures. 

(c) A fuse box, fuse, and two snap switches in the line from the trolley to the 
governor and air compressor, protecting the latter from any excessive flow 
of current and enabling the current supply to the compressor to be entirely 
cut off when desired. 

(d) Two main reservoirs to which the compressed air is delivered from the air 
compressor, where it is cooled and stored for use in the brake s^'stem. ^Yhere 
the chmatic conditions render it necessary, a radiating pipe should be installed 
between the compressor and the first reservoir and between the two reservoirs 
to assist in the cooling process. 



AIR BRAKES 175 

(e) A check valve installed between the main reservoirs and the emergency 
valve, to prevent a back flow of air into the main reservoirs when two motor 
cars are operated together. This being the case, each compressor is required 
to supply the air used for braking purposes on its own car. 

(f) A safety valve connected to the first main reservoir, which protects against 
excessive main-reservoir pressure should the compressor governor, for any 
reason, become inoperative. 

(g) Two brake valves, one at each end of the car, through which (1) air is 
allowed to charge the emergency pipe and to exhaust from the straight air 
application and release pipe when releasing the brakes; (2) air enters the 
straight air application and release pipe when applying the brakes; (3) the 
flow of air to or from the brake sjstem may be prevented, as when the brakes 
are being held apphed; and (4) the air in the emergency pipe is allowed to 
escape to the atmosphere in emergenc}' applications. 

(h) An exhaust muffler placed under the platform to deaden the brake valve 
exhaust. 

(i) Just below the brake valve a pipe leads from the emergency pipe to the 
black hand connection of the duplex air gage, which hand shows main-reser- 
voir pressure, as the emergency pipe is always charged to main-reservoir 
pressure, except when an emergency apphcation of the brakes is made, as 
explained later. 

The red hand of the duplex air gage is connected either to the brake cyUnder 
direct or to the piping so as to show brake cylinder pressure. 

(j) An emergency valve, connected to the brake cyUnder head (or pipe bracket 
if used) which (1) controls the flow of air from the reservoirs to the brake 
cylinder when applying the brakes; (2) controls the flow of air from the 
brake cylinder to the atmosphere when releasing the brakes; and (3) automati- 
cally maintains brake cylinder pressure against leakage, keeping it constant 
when holding the brakes applied. 

(k) A brake cylinder, with a piston and rod so connected through the brake levers 
and rods to the brake shoes that, when the piston is forced outward by air 
pressure, this force is transmitted through said rods and levers to the brake 
shoes and appUes them to the wheels. 

(1) A conductor's valve (furnished when ordered) located inside each car, 
enabling the conductor to apply the brakes if necessary. 

(m) Various cut-out cocks, air strainers, hose couplings, dummy couplings, 
etc., the location and uses of which will be readily understood from the 
explanations wtiich follow. 

(n) While not a part of the air-brake apparatus proper, the car is usually 
equipped with two air alarm whistles, one at each end of the car, to be used 
as a warning of approach, with the necessary whistle valves and cut-out 
cocks. 

Two lines of pipe — the emergency pipe and the straight air application 
and release pipe — extend the entire length of the car and train, when two or 
more cars are coupled together, being provided with suitable hose and coup- 
lings at the ends of the cars. The cut-out cocks in these pipes, located just 
back of the hose connections, should always be enclosed at each end of a 
single car or train and always open between cars which are being operated 
together as a train. 



176 AIR BRAKES 

Equipment on Non=Motor Trailers. The equipment of a non- 
motor trailer ear consists of a brake cylinder, auxiliary reservoir, 
emergency valve, straight air application and release pipe, and 
emergency pipe, all of which, except the auxiliary reservoir, have 
been described above. 

In addition, an auxiliary reservoir is used on a non-motor 
trailer car to furnish an independent supply of air for applying the 
brakes on that car when an application is made. The auxiliary 
reservoir pipe is connected to the emergency valve in the same 
manner as is the main reservoir supply pipe on a motor car. The 
auxiliary reservoir is charged from the emergency pipe by way of 
the emergency valve. 

OPERATION RULES FOR ''SME" BRAKE EQUIPMENT 

The following rules furnished by the Westinghouse Company 
for operating the "SINIE" brake equipment are intended to cover in 
a condensed form the important instructions to be observed in 
handling this equipment in service. 

Charging. Before starting the air compressor, see that the following 
cocks are closed: the drain cocks in the reservoirs; the cut-out cocks (if used) 
under the non-operative brake valves, also under the whistles not to be operated ; 
and the cut-out cocks in the emergency and straight air pipes at the head and 
rear end of the car, or of the trains when two cars are coupled together. 

See that the following cocks are open: the cut-out cock, if any is used, 
in the emergency pipe under the brake valve to be operated; governor cut-out 
cock; the cut-out cock under the whistles to be operated; and all the emergency 
pipe and straight air pipe cut-out cocks between cars. 

See that all hand brakes are fully released. The fuse in the compressor 
circuit must be in place and must be **live". 

Place the handle of the brake valve to be operated — all other brake valves 
being in lap position — in release position and start the compressor by closing 
the switches in the compressor circuit on each motor car. 

Do not attempt to move the car until the gage shows full main-reservoir 
pressure. 

Running. Keep the brake valve handle in release position when not being 
used. In event of sudden danger, move the brake-valve handle quickly to 
emergency position, at the extreme right, and leave it there until the car has 
stopped and the danger is past. 

If the brakes apply while running over the road, due to bursting of hose, 
etc., move the brake-valve handle to emergency position at once, to prevent 
loss of main-reservoir pressure, and leave it there until the car or train stops 
and the danger is past. The cause of the application should be located and 
remedied before proceeding. 



AIR BRAKES 177 

Service Application. To apply brakes for an ordinary stop, move the 
brake-valvo handle to cither one-car service position or two-car service position 
depending iij)on the conditions existing and resuUs desired. When the desired 
brake-cyhnder pressure has been obtained, as shown by the red hand of the air 
gage, the brake-valve handle should be placed in laj) position, where it should 
remain until it is desired either to release the brakes or to make a heavier appli- 
cation. 

How heavy an application should be made, and w hether a full application 
should be made at once or the brakes graduated on, depends upon the circum- 
stances in each particular case — such as the speed and weight of the train, 
condition of the rails, grade, kind of stop desired, and regard for the comfort 
of the passengers. 

Because the retarding effect of a given brake-cylinder pressure is greater 
at low speeds, this fact will result in an abrupt stop, w-ith perhaps danger to lading, 
discomfort to passengers, or slid flat wheels. With high si)eeds, however, a 
heavy initial appUcation should be made in order to obtain the most efTective 
retardation possible when the momentum of the car is greatest. If the brakes 
are applied lightly at first and the braking pressure increased as the speed of the 
car diminishes, it not only makes a longer stop, but the high brake-cylinder 
pressure at the end of the stop will be likely to produce a rough stop, slid wheels, 
and to result in loss of time. 

The best possible stop will be made when the brakes are applied as hard, 
at the very start, as the speed, the conditions of the rails, and the comfort of 
the passengers will permit, and then graduated off as the speed of the car is 
reduced, so that at the end of the stop little or no pressure remains in the brake 
cylinder. 

To properly weigh all these varying factors in every stop becomes, after 
a little practice, an act of unconscious judgment. Careful attention to cause 
and effect at the very start and a real desire to improve are the most necessary 
qualifications in order to become expert in handling this or any other form of 
brake equipment. 

Holding Brakes Applied. The brake-valve handle should be left in lap 
position until it is desired either to release the brakes or to apply them with 
greater force. If the car is to be left standing with the brakes applied for any 
length of time, the air brakes should be released and the hand brakes set. 

Release. The brakes are released, as with any straight airbrake, by placing 
the brake-valve handle in release position and leaving it there, if it is desired 
to fully release the brakes; or, if it is desired to graduate or partially release 
the brakes, by moving the handle to release position for a moment, then back 
to lap position, repeating this operation until the car is brought to rest, only 
enough pressure being retained in the brake cylinder at the end of the stop to 
prevent the wheels from rolling. 

Emergency. Should it become imperative to stop in the shortest possible 
time and distance, to save life or avoid accident, move the handle quickly from 
whatever position it may be in to cmergcncij position, which is at the extreme 
right, and allow it to remain there until the car stops and the danger is past. 

When releasing after an emergency application, it will be observed that 
the release takes place slowly. This is intentional, the equipment being so 
designed that when such a release is made, a fixed period of time must elapse 



178 



AIR BRAKES 



from the movement of the handle to release position until the brake releases. 
This is not only to secure an additional protection but to discourage the 
unnecessary use of the emergency position of the brake-valve handle. 

Changing Ends. When changing from one end of the train or car to the 
other, place the brake-valve handle in lap position; close the cut-out cock (if 
used) in the emergency pipe under the brake valve; then remove the handle, 
after placing it on the brake valve at the other end, move it to release position 
and open the cut-out cock (if used) in the emergency pipe under this brake valve. 

GRAPHICAL REPRESENTATIONS OF PROPER BRAKING METHODS 

Much time can be saved by a proper use of the brake in making 
service stops, in adapting the brake cyUnder pressure to the speed at 
which the car or train is moving. For example, for high speeds 



Time 



10 Seconds 



/5 



^O 



1 r 



I r 



T — r 




Distance of Stop in Feet 
Fig. 138. Diagram Showing Distance of Stop for Electric Car in Feet 

make a full application and graduate the pressure off as the speed 
reduces. To handle the train smoothly, make a heavy application 
and soon enough so that if held on, the train would stop short of the 
mark. Then as the stopping point is approached, graduate the pres- 
sure off of the brake cylinder so that little remains when the stop is 
completed. If on the level track, complete the release; if on a grade, 
hold until the signal to start is given, then release. 

Proper and Improper Manipulation. A clear idea of proper and 
improper methods of brake manipulation is shown graphically in 
Fig. 138. The dotted lines show the usual method of operation and 
the results obtained with the old-style brake apparatus. Assume 



AIR BRAKES 



179 




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180 



AIR BRAKES 



the speed to be 40 m. p. h. when the apphcation is begun. The 
brake is appUed in a series of steps or graduations so that in about 
16 to 17 seconds, maximum cyhnder pressure has been reached; but 
meanwhile the train has been brought nearly to a standstill with 
the highest brake-cylinder pressure being developed at the time the 
speed is lowest and, consequently, with great tendency on the part 
of the wheels to slide, making it necessary to get rid of this high- 
cylinder pressure at once or come to a stop with an unpleasant jerk. 
A stop by this method is made in say 750 feet. 

The full lines illustrate the proper method and show what is 
possible in the way of smoothness of stop, accuracy of stop, saving 
of time, and freedom from tendency to wheel sliding. The maxi- 

Conduclors Valve ""^tr: 

B-3 standard ^ 

B-^ Oplional for Ihis 
Eijuipmenl when^ Pipe is Used 



,11 III III 
S>'£*2 3trainer 





E&'LDummy 
Coupling 



D Emergency 



a'CutOuf Cock 
P.uKiliari^ Ffeservoir 
tianaer &^ Block 

/fu^ilfara f^eservoir 

-Drain Cock 




Local Conditions Determine Whettierltie Emergency Valve be Placed 
en Bracket or on the Brake Cylinder Head 



Fig. 140. 



Piping Diagram for Westinghouse "SME" Brake Equipment (with 
Type "D" Emergency Valve) for Trailer Car 



mum cylinder pressure is obtained at once when the speed of the 
train is highest and the holding power of the brakes least effective. 
At the end of about ten seconds, when the speed has been reduced 
to say 20 m.p.h. and the brakes are "taking hold" more powerfully, 
a part of the cylinder pressure is released — enough (25 pounds) 
being retained in the cylinder to maintain as high a rate of decelera- 
tion as possible without danger of sliding of wheels. This operation 
is repeated as may be necessary to keep the retarding force (brake- 
cylinder pressure) in its proper relation to the decreasing speed of 
the train. A stop by this method is made in say 680 feet — 70 feet 
shorter than by the improper method — and plainly with much 
greater smoothness, less tendency to wheel sliding, in shorter time, 
and with the brake-cylinder pressure nearly or completely exhausted 
and the system practically fully re-charged. 



AIR BRAKES 



181 



The point A in the diagram shows that during the stop by the 
first method the train was running at a speed of over 15 m.p.h. 
when passing the point at which it U'ould have come to a stop, if the 
second and correct method of brake operation had been followed. 
Assuming a weight of 100,000 pounds for the train, it therefore 
possessed at the point A about 1,200,000 foot-pounds or GOO foot- 
tons of energy, which would have been harmlessly dissipated had the 
brakes been manipulated properly. Such a comparison as this 
shows clearly that the question of which method of operation to pur- 
sue is not of theoretical but of vital and practical importance. 

DESCRIPTION OF EQUIPMENT 

Figs. 139 and 140, illustrate diagrammatically the "SME' 
brake equipment, including piping and relative location and names 
of all parts. 

Type "D=EQ" Motor=Driven Air Compressor. Type ''D-EG" 
air compressor is manufactured for use with 110-, 220-, and 600- volt 
direct-current operation, 
also two- and three-phase 
alternating current at 
110, 220, 440, and 550 
volts, and for 25, 40, or 
60 cycles. It can also be 
furnished to operate on 
single-phase 100-volt cur- 
rent, and 15 or 25 cycles. 

Fig. 141 illustrates 
the general appearance of 
the air compressor and 
Fig. 142, shows the 
method of cradle suspen- 
sion under the car when in service. Figs. 143 and 144 illustrate its 
form of construction. Fig. 143 being a horizontal section and side 
elevation, and Fig. 144 an end elevation with a vertical section of the 
cylinder. 

Type of Compressor. The compressor is of the duplex type, 
having pistons moving in opposite directions. Its action in com- 
pressing air is as follows: Air is drawn through suction screen 4 




Fig. 141. Type "D-EG" Motor-Driven Air Compressor 

Courtesy ofWestinghouse Air Brake Company, 
Wilrnerding, Petinsylvania 



182 



AIR BRAKES 



(which is now usually replaced by a cylinder cover with a piped 
suction to any convenient place for securing pure air) in the cylinder 
cover 25 to chamber J through chamber H (which is filled with 
curled hair), thence by raising either one of the two steel inlet valves 
ly through ports C or C^ into cylinders A ov B (depending upon 
which piston is moving away from the cylinder cover). On the 
return stroke the air is forced through either port K or X^ past 
one of the discharge valves 2, then into chamber E, from which it 
goes into discharge pipe D. Both the inlet and discharge valves 
are made of pressed steel tubing and are, therefore, light and easily 
removable. The inlet valves are accessible by removing caps 5, the 
discharge valves by removing caps 26, Inasmuch as all the valves 
close by gravity, there are no springs to break, corrode, or lose their 
temper. 

Pistons. The pistons 5 are accurately fitted with rings 6. For 
the best results, it is essential that the packing ring be installed 

with the square seg- 
ment of the ring near- 
est the wrist pin. 
When this is done, the 
angle portion is next 
the pressure end of the 
piston, which is neces- 
sary in order that the 
ring joints may lap in 
such a way as to pre- 
vent leakage. 

To insure correct replacement of pistons and rings, a letter is 
stamped at the top of the outside flange of each cylinder, on the 
outside face of each piston, and on the inside face of the joint of each 
packing ring segment. In addition to this letter, each packing ring 
segment is also stamped. 

Connecting Rod Construction. The wrist pins 7 are of steel, 
hardened, ground, and secured in place by a set screw 30; a bronze 
bushing 8 in the connecting rod 9 works on them. The crank end 
of the connecting rod is lined, and has a strap 10 hinged at its lower 
end and secured by an eyebolt 11 at the upper end. On this bolt 
between the two parts are thin steel washers 12, which may be 




Fig. 142. Westinghouse Type "D-EG" Motor-Driven 
Air Compressor Suspended in Cradle under Car 



AIR BRAKES 



183 



removed as the bearing wears, and the strap then tightened down 
on the remaining ones and locked with the jam nut. 

The center hne of tlie c^ lindcr is a Httlc above the center hne of 




Fig. 143. Sectional Views of We.stinghouse Type "D-EG" 
j\Iotor-Driven Air Compressor 

the crankshaft, so that the angularity of the connecting rod may be 
reduced during the period of compression, thereby reducing the 
vertical component of the thrust and consequently the wear on the 



184 



AIR BRAKES 



cylinders. The shaft must, however, always run with the com- 
pression part of the stroke on the upper half revolution, i.e., clock- 
wise when viewed from the gear end. The crankshaft I4 is made of 
heavy forged steel and, besides having ample end bearings 13 and 
i^ of bronze, is provided with a large babbitt-lined center bearing 
which is a part of the crankcase cylinder casting 17. 

Lubrication, The parts mentioned above are all lubricated 
from a bath of oil, poured into the dust-proof crankcase through a 
special fitting 18, which acts as a gage of the oil level; the fitting is 



A|R0I8CHARG£. 




Fig. 144. Part Section of Westinghouse Type "D-EG" Motor- 
Driven Air Compressor 

closed by a suitable screw plug 19 which is secured to it by means of 
a chain. On the overhanging end of the crankshaft is the gear 
wheel 20, made of semi-steel mixture in two halves and bolted 
together to form the well-known "herringbone" type of gear. It 
is forced onto the shaft over a square key and secured by the nuts 28. 
Motor, The motor is of the series type with a cast-steel magnet 
frame 50, having a prolongation on the commutator end, provided 
with an opening to permit of ready access to the brushes and com- 
mutator. This opening has a door 51 hinged to the frame and 
tight-fitting so as to exclude rain and dust. In the ends of the 



AIR BRAKES 



185 



frame are centered housings 52 ^ 53, and 79, which carry the arma- 
ture bearing at the ends of the motor; 52 and 79 are provided with 
an oil well with filling hole so located that it is impossible to flood the 
interior of the motor with oil. Cast-iron bearing shells 73 and 74, 
of ample proportions, with babbitt inserts, are centered in the 
housings and secured by means of set screws 75 and 76. Each 
bearing has two oil rings 77 and 78, which insure the proper lubrica- 
tion of the shaft as long as any oil remains in the wells. An over- 
flow passage, below the opening into the motor at the pinion end, 
leads to the bottom of the gearcase in the earlier forms of the com- 
pressor and to the crankcase in the latter forms, effectively prevent- 
ing any of the gear lubricating oil, which might work through the 
pinion bearing into its oil well, from flooding the motor. 

Two of the four field poles are a part of the frame 50, the other 
two, 58, being made up of laminations of soft sheet steel riveted 
together and bolted to the frame, thereby 
also securing in place the field coils 59. The 
armature 60 is built up of electric soft sheet- 
steel punchings. The commutator 61 is of 
liberal length, with deep segments insulated 
with the best grade of mica. 

Type "J" Electric Compressor Gov= 
ernor. The location of the compressor gov- 
ernor is" shown in Fig. 139. That shown is 
a type used in connection with the smaller 
class of compressors and differs from the 
type under discussion. Its purpose is to 
start and stop the compressor, in order to 
maintain a predetermined pressure, by alter- 
nately making and breaking the circuit lead- 
ing to the motor. The general appearance 

of the governor is shown in Figs. 145 and 14G, while Fig. 147 is a 
vertical diagrammatic section. 

As may be seen, the governor is made up of two distinct portions, 
one being a switch and the other a pneumatic regulator. Current 
from the trolley to the compressor is made or broken by the switch 
spider ^5, attached to the switch piston and rod 16 and making con- 
nection between finger contacts 5 when the governor is in ''cut in" 




Fig. 1 to. Westinghouse Tj-pe 
"J" Electric Compres- 
sor Governor 



186 



AIR BRAKES 



position. The governor operates equally well with either direct or 
alternating current. It is thoroughly insulated and is covered by 
an iron casing held in place by the thumb nuts 13. The admis- 
sion of air to and exhaust air from the cyHnder W is controlled by 
the regulating portion of the governor and takes place through port 
g which, when the governor is in the "cut-in'' position, is connected 
by cavity h in the slide valve 76 with the exhaust port / leading 
to the atmosphere. 

Referring to Fig. 147, main-reservoir air enters the governor 
at the pipe connection marked "To Main Reservoir", and flows 
through the passage a to the space B between the double pistons 
25. From B it flows through ports e and j to space K on the face 

of the diaphragm 
60, on the opposite 
side of which is a 
spindle 61 held 
against the dia- 
phragm by the reg- 
ulating spring 62. 
The stem of spindle 
61 projects through 
the regulating nut 
63 to the end of 
the "cutting-out" 
regulating valve 
28, which is held 
firmly against the end of the spindle or its seat, as the case may be, by 
the regulating valve spring 27. So long as the main-reservoir pressure 
is less than that for which regulating spring 62 is adjusted, the latter 
holds the spindle 61 over so that the "cutting-out" regulating valve 
28 remains seated. If the main-reservoir pressure is increased 
so that its pressure on diaphragm 60 is able to overcome the pressure 
on the regulating spring 62 on its opposite side, the spindle 61 will 
be forced back toward regulating valve 28, which it Hfts slightly 
and permits the air in chamber C to flow through port I and space 
M past the regulating valve to the atmosphere. 

As the pressures on the smaller end of the double piston are 
balanced at this time and the pressure in chamber B on the right- 





Fig. 146. Westinghouse Type "J" Electric Compressor Governor 
in Cut-in Position — Cover Removed 



AIR BRAKES 



187 



hand side of the larger end of the double piston is now much higher 
than that in chamber C, the pistons and attached slide valve are 
moved to the left to "cut-out" position, as sho^\^l in detail at the 
right, Fig. 147. It will be seen that the first movement of the slide 




Fig. 147. 



Diagrammatic Sectional View of Westinghouse Type 
Electric Compressor in Cut-in Position 



'J" 



valve 76 opens port b to chamber B, permitting air at main-reservoir 
pressure to flow through port b to the piston ''seal" 21, The area 
of port b, however, is so small that tlie main-reservoir pressure 
acting therein is not able to overcome the pressure of spring 17, 
which holds the switch piston to its seat. But a further travel of 



188 AIR BRAKES 

the slide valve opens port g, which allows air at main-reservoir 
pressure to flow to the air cylinder W, thus breaking the "seal" 
of the piston and the main-reservoir pressure then acts on the entire 
area of the piston, causing it to move outward very rapidly and break 
the circuit. By having port b open before port g, a free flow of 
high-pressure air to the space W below the switch piston is insured 
and a "quick-break" obtained, which eliminates any tendency to 
cut out slowly. During this movement the air above the switch 
piston is compressed, and forced through ports y and z in the hollow 
rod to the atmosphere. The ports z are so placed that they pass 
the ends of the contact fingers just when the circuit is broken and 
the quick piston movement causes the air in X to be expelled with 
such force as to make an effective and complete pneumatic blow-out. 

In this position of the slide valve 76 it will also be seen that 
cavity h connects port e to the exhaust port / and atmosphere, 
thus relieving diaphragm 60 of pressure and permitting the regulat- 
ing valve 28 to seat. Air from chamber C can then no longer escape 
to the atmosphere and it rapidly becomes equal in pressure to that 
in chamber B (due to flow of air through the small leakage port 
shown in the large double piston). Both ends of the double piston 
are then balanced and the parts remain in "cut-out" position until 
the governor is "cut-in" as follows: A branch from port a permits 
air at main-reservoir pressure to flow through port q to p and the 
space on the face of diaphragm 71, on the opposite side of which 
is a spindle 67 held against the diaphragm by the "cutting-in" 
regulating spring 70. The stem of the spindle projects through 
the regulating nut 68 and the "cutting-in" regulating valve 65 
is held against the end of the stem by the regulating valve spring 66. 
So long, therefore, as the main-reservoir pressure on the face of the 
diaphragm 71 is greater than the pressure of the regulating spring 
70 on its opposite side, the regulating valve 65 will be held to its 
seat by the stem of spindle 67 and the port n is then closed. 

After the governor has been "cut-out" as explained above and 
the main-reservoir pressure falls to such a point that the air pressure 
on diaphragm 71 is no longer able to overcome the pressure of the 
regulating spring 70 on its opposite side, the latter moves the spindle 
over so as to permit the regulating valve spring 66 to raise the 
regulating valve 65 slightly from its seat. This permits the air 



AIR BRAKES 



189 



in chamber D, back of the smaller end of the double piston, to escape 
through port n and past the regulating valve 65 to the atmosphere. 
The larger end of the double piston is balanced at this time and the 
pressure in chamber B, therefore, forces the smaller piston back 
to the position shown in Fig. 147, carrying with it the large piston 
and slide valve, exhausting the air from the air cylinder W through 
ports </ and h and exhaust port/ to the atmosphere, and allowing the 
piston spring 17 to force the piston 16 and the circuit closer 4^ 
back to ''cut-in" position. It will be seen from the illustration 
that when the double piston moves to "cut-in" position, as explained, 
a projection boss on the outside face of the small piston closes the 
connection between chamber D and port n, so that the pressure 
in D has no escape when the governor is cut in. Chamber D is 
very small and as the small piston and its packing ring, when fitted 
as tight as is practicable, are still not absolutely air-tight, the slight 
leakage past the small piston soon equalizes the pressures in D 
and B, and, as the pressures in C 
and B are also equal, both double 
pistons are again balanced and the 
parts remain in ''cut-in" position 
until the governor is "cut-out" as 
already explained. 

The governor is adjusted for a 
cutting-in pressure of 50 pounds and 
a cutting-out pressure of 65 pounds. 

Type "M=18" Brake Valve. 
The "M-18" brake valve. Fig. 148, 
is of the rotary type and it is fitted 
with a removable handle. A top 
view of the valve. Fig. 149, shows 
the different position of the handle, while a vertical section illustrates 
the arrangement of the ports, etc. The positions of the handle, named 
from left to right are, release, lap, one-car service, two-car service, and 
emergency position. The pipe connections are as follows: 

(a) Straight air application and release pipe, leading to the emergency valve. 

(b) Emergency pipe, which also leads to the emergency valve. 

(c) Brake valve exhaust pipe, leading to the exhaust mufller under the platform. 

(d) Reservoir pipe, leading to the emergency valve and to which the reservoir 
is connected through the check valve. 




Fig. 148. Westinghouse "M-18" 
Brake Valve 



190 



AIR BRAKES 



Duplex Air Gage. The duplex air gage, Fig. 150, is installed 
in the direct line of vision of the motorman, when operating the 
brake valve. The pipe connection for the brake-pipe gage hand is 
taken off from the brake pipe just below the cut-out cock. The 




Fig. 149. Westinghouse "M-18" Brake Valve in Plan 
and Actual Section 



connection for the main-reservoir gage hand is taken out from the 
emergency pipe. 

Type "D" Emergency Valve. The Type ^'D" emergency valve 
is illustrated in Figs. 151 and 152. It contains an equalizing piston 
11 y a slide valve 13 (which serves as a means of exhaust only), 
an emergency piston 24 and slide valve 25, Communication be- 
tween the reservoir and brake cylinder is controlled by the poppet 
valve i7. The valve may be attached to the cylinder head or to 



AIR BRAKES 



191 



a bracket under the car floor or on a stand inside of the car. The 
emergency reservoir and straight air and release pipes are connected 
directly to the cylinder head. 




For S' Iron Pipe 
org'Outside Dia. 
Copper Tubing 



Fig. 150. Westinghouse Duplex Air Gage 







Brake Cylinder. The brake cylinder employed is illustrated 
in Fig. 153. The piston S is connected to the brake rigging in 
such a manner that it moves only 
when the power brake is used. 
When the hand brake (if pro- 
vided) is used, no movement of 
the piston occurs. The piston 
rod is made hollow to receive the 
push rod Hy which is attached to 
the levers of the foundation brake 
gear. The release spring 9 forces 
the piston to release position 
when the air pressure is ex- 
hausted from the brake cylinder. 
The packing leather 7 is held 
against the cylinder wall by the 
expander 8 which insures an air- 
tight piston. 

Conductor's Valve. This valve is located in a convenient 
position in the car and is preferably fitted with a cord attached 




Fig. 151. Westinghouse Type "D" 
Emergency Valve 



192 



AIR BRAKES 



to its handle and running the entire length of the car. It is to be 
used only in eases of necessity or emergency. It is connected to 




^ 



Fig. 152. Actual Section and End View of Westinghouse Type "D" 
Emergency Valve 



the emergency pipe by a branch pipe and permits air to flow directly 
from the emergency pipe to the atmosphere, setting the brakes in 



s^r-^f 



m: 




Fig. 153. Diagram of Brake Cylinder 

emergency. The style of the valve is of the non-self-closing type 
and must be closed by hand after being used. 

METHOD OF OPERATING "SME" BRAKE EQUIPMENT 

In giving an explanation of the operation of the "SME" equip- 
ment, reference will be made to the diagrammatic views shown in 



AIR BRAKES 



193 



Figs. 154 to 158. In this discussion it is assumed that the non- 
operative brake valve on the rear of the car is in lap position. 

Charging. With the reservoirs charged and the brake-valve 
handle in release position, air flows from the main reservoirs through 
the check valve to the brake valve and into the emergency pipe. 
A feed groove i around the emergency piston 24 permits an equal- 
ization of pressure in the emergency pipe with main reservoir pressure, 
which is assisted by a small port through the rotary valve 5 of the 
brake valve in all positions except emergency. 

Service Application. To apply the brakes, move the brake- 
valve handle to either one-car service position or two-car service 



M-l8Bral<e Valve 
Operable 



Brake Ci/linder 




UM.fi 




^///yy,V/,'/ 



nidBrvke Valve 

Ncn -Operoh^'C ■ 



^fa^u ^ \jMU]iM^,.!\ 




^:lt 



J 



I 



5lraighlf\ir Fif: plica liort and, 
Releas e Pipe 



Emerqenci/ Pipe 



To Ho^c Connections. 



Fig. 154. Diagram of One-Car Service, "SME" Equipment with 
Type "D" Emergency Valve {W estinuhouse) 

position, depending upon the length of train, speed, condition of 
rail, kind of stop desired, etc. In one-car service position a rela- 
tively small opening (see port h, Fig. 154) is made from the reservoir 
pipe to the straight air application and release pipe and this posi- 
tion is, therefore, used with a single car or when running at slow 
speeds, and so on. In two-car service position the opening from the 
reservoir pipe to the straight air pipe is larger (see port h, Fig. 
155), and this position is, therefore, used with trains of greater 
length, when running at higher speeds, or, in general, when a heavier 
application of the brakes is desired. 

In response to this movement of the brake-valve handle, air 
is admitted from the reservoir pipe to the straight air application 



194 



AIR BRAKES 



and release pipe and emergency valve through port r, cavity c, 
and ports b, n, and o of the brake valve, thence through port Z, 
cavity M of emergency slide valve 25, ports k and k' to chamber 
B and the face of equalizing piston 11, forcing it inward. The 
first movement of the emergency valve piston takes up the lost 
motion between the collar on the stem and the exhaust valve 13, 
and after closing the exhaust ports x and n, cutting off the brake 
cylinder from the atmosphere unseats check valve 17, Communica- 
tion is thus estabhshed between chambers I) and R and the brake 
cylinder so that air is admitted direct from the main reservoirs 
to the brake cylinder. When the pressure in the brake cylinder 



f1-/8 Brake Valve- 
Ope rah ve 



Brak& C^j^h rider 




^To Hose Co'^'^ecUons 



Slraighl fiir Application and 
Relsas& Pipe. 



Emergencu Pipe^ Tofio3e ConnectionSi 



Fig. 155. Diagram of Two-Car Service, "SME" Equipment with 
Type "D" Emergency Valve (Westinghouse) 

almost equals that in chamber B, spring 18 will drive the equalizing 
piston outward until the check valve 17 seats. A further rise of 
pressure in chamber B will move the equalizing piston inward, 
unseating the check valve and causing an equal rise in brake-cylinder 
pressure. 

Holding Brakes Applied. When the desired brake-cylinder 
pressure has been obtained, the brake-valve handle should be 
placed in lap position. This causes the parts of the emergency 
valve to assume lap position, Fig. 156, and holds the brakes applied. 
In this position communication is cut off between the reservoir 
pipe and the straight air application and release pipe so that no 



AIR BRAKES 



195 



further supply of air is admitted to chamber B of the emergency 
valve, and check valve 17 h seated so that no air is admitted to 



M-Je Brake yal^/e 
Operative 




A1i8 Broke Valve 



I - — ^-^^ 



.^.^mii'j . 




■Straight fiir /Application s^ Release EmerqencuPipe 
fipe T V r 

Fig. 15G. Diagram of Service Lap Position, "SME" Equipment with 
Tjpe "D" Emergency Valve {W e&tinghouse) 

the brake cylinder. However, should leakage occur in the brake 
cyHnder, it will be automatically maintained, for a decrease of 



M-18 Brake Val^e 
Operative 



ft ft ft ft ft n n rn n fl ^ 




H-ieBrake Val'/e 
Non-Operative 

"TZZZZZZZZZZ?, 



5. r*- 




7^ "T 

Straight /Iirffpplicalton y £mer(jencu Pipe ^ 



T 



ToHose 
Connections 



ffeleasePipe 

Fig. 157. Diagram of Release Position, "SME" Equipment with 
Type "D" Emergency Valve {Westinghousc) 

pressure in chamber 7?, which is always open to the brake cylinder, 
below that in chamber B on the opposite side of the piston will 



196 



AIR BRAKES 



cause piston 11 to move inward again, unseating check valve 17 
and admitting more air to the brake cyUnder to replace that lost 
by leakage. 

Releasing. In releasing the brakes after an application, Fig. 
157, the air in chamber B of the emergency valve is exhausted 
through ports A:' and k, cavity M of slide valve 25, and port I to the 
straight air pipe, thence through ports n, o, and p in the rotary 
valve seat 2, cavity h and port j in the rotary valve, and port m to 
the atmosphere through the exhaust pipe. The greater pressure in 
chamber R then forces the equalizing piston to release position, 
uncovering the exhaust ports x and u and allowing the air from the 
brake cylinder to escape to the atmosphere. 

Emergency Application. The emergency position of the brake 
valve should be used only when it is necessary to stop the car within 

M-18 Brake l/bli'e 
Operati{^e 



M-W Brake. Valve 




'*^To Hose. Connections ^Slraighl JJir /Jpphcafton and ^ Crneraencu Pipe. 



Release Pipe 

Fig. 15S. Diagram of Emergenry Position, "SME" Equipment with 
Type "D" Emergency Valve {W estinghouse) 



the shortest possible distance to save life or avoid accident. In 
this position. Fig. 158, the straight air application and release-pipe 
connection is blanked in the brake valve, while the emergency-pipe 
air is exhausted to the atmosphere through port q in the rotary 
valve seat, ports h and j in the rotary valve, and port m in the seat, 
thus reducing the pressure on the upper side of the emergency piston 
2Jj., which is forced to the upper end of its stroke by the main-reser- 
voir pressure on the under side, carrying with it sHde valve 25. This 



AIR BRAKES 197 

cuts off the straight-air pipe connection and admits air from the 
main reservoirs through ports d and <:/', k and k' , to chamber B, 
forcing piston 11 to its extreme inner position. This action opens 
the check valve 17 wide and permits the air from the main reservoir 
to flow rapidly into the brake cylinder until the pressures equalize. 
In the same way also, should a hose burst or uncouple, or pipe 
break, the resulting rapid drop in emergency pipe pressure will 
insure an emergency application of the brakes as described. 

Upon restoring the pressure in the emergency pipe by placing 
the brake-valve handle in release position, the equalized pressure 
on either side of the emergency piston 2^ permits spring 20 to return 
the piston to its normal position, thus releasing the pressure back 
of the equalizing piston through the straight air pipe and brake valve 
to the atmosphere, at the same time allowing brake-cylinder air to 
escape through the exhaust ports x and u in the emergency valve. 

Axle=Driven Compressor Equipment. Axle-driven compressors 
are now practically extinct. When used, a slight change in the 
piping is necessary from that above described. Since the com- 
pressor is mounted on the truck and has some movement relative 
to the car frame which carries the reservoir, flexible hose connections 
are necessary to make connections to the reservoir and also to the 
compressor regulator. A small reservoir is also used which receives 
air from the compressor. This small reservoir is connected to the 
main reservoir by a pipe containing a regulating valve. The air 
attains a pressure of about 35 pounds in the small reservoir before 
any air passes into the main reservoir. This 35-pound pressure in 
the small reservoir is attained while the car runs about 100 yards 
and is available for applying the brakes. This always insures air 
for operating the brakes, if the car previously runs a short distance. 
With this exception, the piping would be the same, and no further 
description is thought necessary. 

Storage Air=Brake Equipment. If a car is fitted with a storage 
air-brake equipment, no comjiressor is installed on the car. The 
compressed air which is used for braking is carried on the car in large 
reservoirs. The general scheme of a storage equipment is shown in 
Fig. 159, which illustrates an obsolete type of the straight air-brake 
system as applied to a single car. Two large reservoirs connected 
by a one-inch pipe carry air at high pressure. These reservoirs 



AIR BRAKES 



199 



deliver air through a reducing valve to a service reservoir. The 
pressure in the service reservoir corresponds to that in the reservoir 
previously described. Other than these parts just mentioned, the 
straight air-brake system and the storage air-brake system are the 
same. 

Train Air Signal. As the size of electric cars and the length of 
trains increase, a reliable signal system becomes more and more a 
necessity. The systems now used are quite similar to those employed 
on steam roads, one of which has already been explained. 

Stopping a Car. The brake equipment of all electric cars is 
calculated with reference to the unloaded weight of the car, that is, 
the parts are so designed 
that there will be no 
danger of slipping the 
wheels when the car is 
unloaded. In stopping 
a car, the forces which 
act to retard its motion 
are: (a) the resistance of 
the atmosphere; (b) the 
frictional resistance of the 
journals and track; and 
(c) the resistance of the 
brake shoes on the wheels. 

When the brake is 
applied, the car pitches 
forward on the front 
truck, and the weight of 
the rear truck is thereby 
decreased. If proper allowances have not been made in proportioning 
the brake levers, the rear wheels will probably slip on the track. If 
the wheels should slip, the distance required in which to bring the 
car to rest would probably be greater than that required had the 
wheels not slipped. In bringing a car to rest, the energy of trans- 
lation of the entire car and the energy of rotation of all the wheels 
and motors must be absorbed by friction. To do this efficiently 
and safely in the shortest possible time is the purpose of the modern 
brake system. 























































^ 50 




































































/7 


































— 


— 


— 


-- 


V 


y 














^ 






















/ 






















/ 






















IC 


/ 


f 






















/ 


























f 








K 

















lOO ^00 3C0 'fOO 500 600 rOO 800 XO /oco 
Distance in Feet Measured from Point cf thirst 
flpplicalion of Drake 

Fig. 160. Diagram Showing Relation between Speed 
of Car and Distance in Which Stop Can Be Made 
after Application of Brake 



200 AIR BRAKES 

The average person who rides on street and Interurban cars 
knows nothing as to the distance in which these cars can be stopped. 
''In what distance can a modern double-truck electric car be 
stopped?'^ is a question which is frequently asked. In answer to 
this question, Fig. 160 has been prepared. A great many experi- 
ments have been made in stopping cars, with varying results. The 
chief factors which affect the results of such tests are the condition 
of the rails and the character of the material composing the brake 
shoes. Fig. 160 shows graphically the relation between the distance 
required to stop a car and the speed (in miles per hour) at the instant 
the brake was applied. It represents the average result of a large 
number of experiments with a double-truck car fitted with brake 
equipment as described in the preceding pages. With perfect con- 
ditions, the curve ABO would fall above that shown, while with very 
poor conditions, it would fall lower. The value of the diagram is 
made apparent by the following application : 

Example. Find the distance in which a double-truck electric car may be 
stopped, if power is shut off and the brake applied while running at a speed of 
30 miles per hour. 

Solution. Starting on the vertical line OY at 30 miles per hour, follow 
the horizontal line to the right until the curve ABO is reached at the point B. 
From point B, follow the vertical line downward until the horizontal line OX 
is reached at the point C. This point C indicates the distance in feet in which 
the car may be stopped, which in this instance is 440 feet. In the same way^ 
the stopping distances may be determined for cars running at any speeds. 



INDEX. 



INDEX 

"• PAGE 

Air-brake equipment, brief instructions for use and care of_ __ 168 

Air brakes 1-200 

as applied to electric cars 171 

systems developed 171 

brake, early forms 1 

braking an outgrowth of speed 1 

briefi instructions for the use and care of air-brake equipment 168 

characteristics of modern systems 172 

early forms 172 

modern brake equipment 105 

"Sme'* brake equipment 174 

studying 8 

Westinghouse train air-signal system 165 

Air compressors 14 

disorders 24 

mair> reservoir 31 

single-stage type 14 

steam compressor governors 25 

two-stage type 20 

comparison w^th single-stage type 20 

Automatic brake operation 120 

automatic release 124 

charging 120 

emergency 124 

emergency lap 127 

service 120 

service lap 123 

Automatic brake valves 32 

duplex air gage 47 

"G-6" 32 

Automatic slack-adjuster 101 

Axle-driven compressor equipment 197 

B 

"B-6" double-pressure feed valve 50 

Brake cylinder 191 

Brake, early forms 1 

Cramer spring type 2 

developments due to steam locomotives 2 

first railroad type 2 

hand types 3 

Loughridge chain type _ _ 3 



INDEX 

Brake, early forms (continued). page 

stagecoach type 1 

Brake equipment (modern) 105 

distributing valve and double-chamber reservoir 116 

double-pressure control or schedule "U" 107 

high-speed 105 

"LU" passenger-car brake equipment 109 

No. 6''ET" locomotive 110 

"PC" passenger brake equipment 133 

recent improvement 165 

Brakes and foundation brake gear 96 

automatic slack-adjuster 101 

general requirements 96 

leverage 99 

locomotive driver brakes 104 

locomotive truck brakes 104 

C 

"C-6" single-pressure feed valve 47 

Car, stopping 199 

Conductor's valve 90, 199 

Control valve 139 

emergency position 160 

releasing action 151 

release and charging position 141 

service appUcation 143 

D 

*'D-EG" motor-driven air compressor 181 

Distributing valve and double-chamber reservoir 116 

automatic brake operation 120 

independent brake operation 127 

Duplex air gage 190 

E 
"E-6" safety valve 94 

F 

Feed valves 47 

"B-6" double-pressure feed valve 50 

"C-6" single-pressure feed valve 47 

G 

"G-6" automatic brake valve 32 

application position 35 

emergency-appUcation position 41 

lap position 39 

release and charging position 42 

release position 39 

running position 33 



INDEX 
H 



PAQH 



Hand brakes i y * 

High-speed reducing valve _ qj 



I 



Independent brake operation j27 

double heading 23j 

independent application _ j27 

independent release 228 

quick-action cyhnder cap 232 



L 



"LN" passenger-car brake equipment 209 

Leverage _ qq 

Locomotive driver brakes 204 

Locomotive truck brakes ]qa 



M 

Master Car Builders' Association c 

triple- valve tests g 

N 

New York air-brake system 20 

No. 6 "Et" locomotive brake 'equipment 2 10 

arrangement of piping, etc _ 211 

functions and advantages 210 

manipulation of equipment 213 

names of pipes , 2ii 

P 

"PC" passenger brake equipment __ 233 

characteristics _ _ ^oo 

control valve ^oq 

instructions for operating _ 203 

names of various parts and their identification ~_ 234 

special features _ 233 

Pressure retaining valve ___ 07 

S 

"Sme" brake equipment (details) 274 

description of equipment 281 

equipment on non-motor trailers _ " 276 

features __ ~ ^y. 

graphical representations of proper braking methods 178 

method of operating 292 

axle-driven compressor equipment 297 



INDEX 

PA.GE 

"Sme" brake equipment (details), (continued). ^^^ ^^^ 

operation rules 174 

principal working parts 25 

Steam compressor f^'^''^ — -- :::;';_::: 27 

double-top or duplex SD type 29 

double-top "SF" type 25 

single-top "S" type ---" 31 

troubles --- 1^7 

Storage air-brake equipment 

T 

Tables .. ^^j weieht of Westinghouse standard 

general dimensions, capacity, and weignt o ^^ 

steam-driven air compressors ^gg 

Train air signal ' 51 

Triple valves ' ^^ 

plain '_'_"_'_ ^^ 

quick-action '" 62 

tvpe ''K" freight 76 

4pe"L" ::::::: i^o 

TvDe "D" emergency valve 185 

Type ''r electric compressor governor --" jgQ 

Type "M-18" brake valve -- 

V 5 

Vacuum brake ^2 

Valves and valve appliances.--- 32 

automatic brake valves 47 

feed valves ^"^ 

miscellaneous types 90 

conductor's valve 94 

''E-6" safety valve 91 

high-speed reducing valve 87 

pressure retaining valve ---■■-- 51 

triple valves _-- 

W 

^ 10 

Westinghouse air-brake system ;".'"'''-'---'-'-'-'-' ^ 

air compressors ^6 

brakes and foundation brake gear lo 

general characteristics " 13 

operation __ 

valves and valve appUances 4 

Westinghouse air type (first) 4 

Westinghouse plain automatic- 165 

Westinghouse train air-signal system 168 

car discharge valve Ibo 

essentials 

reducing valve _ --- "' _ 

signal valve 



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